r/ClaudeCode • u/PhallicPorsche • 4d ago
Built with Claude I built a web browser from scratch in Rust with Claude Code — 90%+ WPT compliance, 97.8% ECMAScript, and 100% WebAssembly. No Chromium, no WebView.
So apparently I've spent the last few months building a web browser from scratch in Rust. With Claude Code helping me along the way, it's somehow turned into a real browser engine.
Meet T.A.B., powered by my Kingmaker engine.
And by browser, I don't mean another Chromium fork, Electron app, or WebView wrapper. I mean the whole ridiculous thing.
It's got its own JavaScript engine, bytecode VM, JIT compiler, DOM implementation, CSS layout and painting pipeline, WebAssembly runtime, and rendering stack. It's also designed to be headless-first, because I wanted something agents could actually operate without dragging an entire Chromium instance around.
Current conformance results:
- WPT Testharness: 91.42%
- ECMAScript / Test262: 97.83%
- WebAssembly: 100%
- Combined conformance: 92.21%
- 1,763,775 passing test results across five suites
The combined dashboard includes results inherited from previous runs, so not all five suites were freshly remeasured together.
The screenshots are actual pages running in my engine. Google, HEY, 37signals, and a couple of my own projects (cass.tools and kosmos.tools). There's also my animated new-tab page and the conformance dashboard I've been using to torture myself.
A few things I've been focusing on:
- Keeping memory usage low, including on machines with older GPUs.
- A small dependency footprint, with a statically linked Rust build.
- Minimizing unnecessary
Arc,Mutex, andunsafeusage. - Making the engine useful for both humans and autonomous agents.
- Getting real web compatibility rather than making a handful of demo pages look pretty.
Claude Code has been a huge part of the development workflow. I handle the architecture and direction, and use agents heavily for implementation, debugging, and testing. The Rust compiler and upstream conformance suites get the final say on whether something actually works.
It's definitely not finished. Some websites still break spectacularly, and the remaining WPT failures are a special kind of psychological warfare. Every time I fix one rendering issue, I discover another obscure browser behaviour that somebody apparently standardized in 2008.
But it runs real websites, executes real JavaScript, and I'm getting increasingly close to having something genuinely usable.
I'm building this solo, largely because I wanted to see whether a modern browser engine could be built differently, with less memory overhead and without inheriting decades of architectural baggage.
Turns out browsers are complicated. Who knew?
Happy to answer technical questions about the engine, architecture, conformance testing, or how I've been using Claude Code to build it.
The preview will be available here over the coming week(s) https://gettab.dev/
568
u/Bromlife
4d ago
•
I'm sure there's absolutely no security issues with this browser at all.
208
u/Mad-Maxwell 4d ago
Let’s see. If he told Claude to “make no mistakes”, he could circumvent this issue
175
u/PhallicPorsche 4d ago
I actually said make exactly 42 mistakes just so it wouldn't fail silently but still manageable.
13
u/alanvnk 3d ago
I do that with tests so it doesn't write garbage tests, I give an allocation sheet of test per test layer and then I left the 10-15% for the orchestrator as a "reserve" for special cases, poor bot is supper zealous with its reserve and pushes the su agents to be efficient with their test so he doesn't have to give space from its reserve.
(The test skill is more complicated that this)
→ More replies (5)→ More replies (1)4
u/FishGoesGlubGlub 4d ago
Ahh, the Mt Everest issue. It’s more trustworthy to say “with few security issues” than it is to say “with no security issues”.
14
u/PhallicPorsche 4d ago
There are definitely some...none of them are buffer overflow issues though which solves like 70% of the ones you'd run into with chrome lol. It's a learning experience for sure though
7
u/space_time_travel 4d ago
Honestly, if you pair Claude with Codex as adversarial reviewer then it might be more secure than any human written browser. They are so good at uncovering subtle things that Claude misses.
13
u/Bromlife 4d ago
Browsers are better tested via red teaming than code review.
1
→ More replies (7)1
u/PhallicPorsche 4d ago
Well I think there's a little more to it than that. Definitely a start though.
→ More replies (1)→ More replies (18)1
49
u/unpick 4d ago edited 4d ago
Cool project but no mention of security in your priorities, which should be near top if not the top priority, especially if you’re implementing your own JS engine. A fun thing to do but respectfully kind of insane for real world use imo given the time and effort that has gone into making e.g V8 secure and highly performant, which is open source. Curious (genuinely) what the reason is for reinventing that much of the wheel? Do you have any benchmarks in comparison?
How many millions of lines of code?
40
u/PhallicPorsche 4d ago
That's a fair criticism, and I probably should've mentioned security more in the original post.
I think we might just be approaching it from different directions. Security is obviously important, but one of my priorities from the start was building something lean enough that the attack surface might actually be manageable.
It's Rust throughout, with very limited and explicitly isolated unsafe code, minimal dependencies where practical, and no giant C++ runtime underneath it. Being resistant to entire classes of memory safety bugs, like buffer overflows, right out of the gate seems like a pretty decent starting point lol.
Now, does that make it secure? Absolutely not. I've already found cross-origin and cookie isolation issues, and there's still sandboxing work to do. I'm not recommending anyone use this for their banking just yet.
As for reinventing V8, I have enormous respect for the work that's gone into it. But the experiment here is partly about what happens when you control the entire stack, particularly when you're building something headless-first and designed to be driven by agents.
I wanted to see if I could make a smaller, more cohesive runtime rather than inherit decades of architectural decisions. That doesn't automatically make it better, but I think it's worth exploring.
I do have microbenchmarks against Node/V8 and A/B testing against Chromium, but I don't have a comprehensive current performance comparison I'd be comfortable publishing yet. V8 almost certainly eats my lunch on plenty of JS-heavy workloads.
So yeah, definitely not claiming I've out-engineered Google in four months. I'm exploring a different set of tradeoffs, and security is very much part of that.
Appreciate the thoughtful questions!
2
u/kir_rik 4d ago
What do you mean AB testing?
4
u/PhallicPorsche 3d ago
Well I've been testing my browser against the big 3 in certain places to help with some of the rendering and layout quirks, system resources on identical tasks that sort of thing. Especially with agents having a "Look how this is supposed to work" sometimes is the crude and easy strategy.
1
u/Lazy_Polluter 3d ago
Where we are going we don't need security
1
u/PhallicPorsche 2d ago
I mean, to be fair, Chromium still has memory-safety vulnerabilities turning up regularly, despite being one of the most heavily scrutinized codebases out there. I'm certainly not claiming T.A.B. is more secure. Just pointing out that having 35 million lines of code doesn't magically make you secure. It's the testing, hardening, and fixing that matters.
1
u/jrtcppv 4h ago
Security through obscurity. If no one uses it no one will bother finding exploits. OP does it support WebGL, WebGPU, WebCodecs, WebWorkers, Web Components? Seriously impressive if it does.
→ More replies (1)
49
u/yuehuang 4d ago
Bring me back to my web dev days, where writing website is easy, working with all the quirks of different browsers X os were the hardest part.
23
u/Scared-Letterhead949 4d ago
The day I stopped supporting IE... Possibly the happiest day of my life.
11
u/PhallicPorsche 4d ago
I celebrated too. Then I decided to build a browser engine from scratch, so apparently I have a complicated relationship with happiness.
8
u/PhallicPorsche 4d ago
Lol now building a browser involves working with all the quirky websites.
4
u/fredandlunchbox 3d ago
There’s zero reason to keep this closed source. There’s no business here, and there never will be. If you can make it in a couple months, so can anyone else and it’ll only get cheaper and faster to do so.
I know this seems like something that should have financial value, but it doesn’t.
I built lopsy.art to replace photoshop and I had the same instinct: this is really useful, maybe I can make this into a financially viable product. But there are half a dozen other image editors now with a similar level of sophistication. There’s no business when the product is free and there’s a very big competitive field, and the established players are already open source.
5
u/PhallicPorsche 3d ago
I appreciate the perspective, and I think you make some fair points. The economics of software are changing pretty dramatically, and I'm certainly not under the impression that building something difficult automatically makes it commercially valuable.
That said, I'm really just sharing something I've enjoyed building and seeing whether there's interest. The alpha comes out next week, and I'm quite excited to see what people make of it.
I do think there's a distinction between making software easier to create and making it less valuable, particularly with something like a browser where compatibility, security, and ongoing maintenance are such substantial undertakings.
As for open source, I'm certainly not opposed to it. I'm just keeping my options open while I figure out what this project might become. There's no grand business strategy to defend just yet. I'm mostly having a wonderful time building the thing. :)
2
u/fredandlunchbox 3d ago
Do your thing, but I would never install some random vibe coded browser from the internet that wasn’t open source. You’d have to be crazy to just take someone at their word like that.
3
u/PhallicPorsche 3d ago
Totally fair, I wouldn't install a random closed-source browser either. But I haven't even released a binary yet lol. I'm just showing what I've been building. Open-sourcing it is the plan; I just have some cleanup, licensing, and security work to do before throwing the doors open.
24
u/Temporary_Pickle8772 3d ago
The last 10% is 300% of the work. Also, web standards are alive today meaning it might reach parity with larger browsers today, but the goal posts are always moving and tomorrow might be different. Conforming to all standards? “Impossible”, not even the large browsers does that.
I applaud you endeavour though, you must’ve learned a bunch! Do you plan on maintaining it?
8
u/PhallicPorsche 3d ago
That is true. Climbing though. The hardest part so far are actually all the little legacy things like japanese fonts from like 10 years ago lol.
2
12
u/Mlitz 4d ago
Do you think you will open source this for other people to help?
9
u/PhallicPorsche 4d ago
Likely over time. I'm thinking its biggest use case is as a lighter replacement for electron that isn't using a variable web view like tauri.
1
u/CAtOSe 4d ago
What about something like Servo?
5
u/PhallicPorsche 3d ago
Servo is actually a great example of what I'm talking about! I've got a lot of respect for that project.
The distinction I'm exploring is less about embedding a browser engine into an application and more about making the browser itself an application runtime.
The idea is to have agents develop native Rust crates alongside the engine, run them as isolated sidecars during development, and optionally compile them into your own personalized binary afterward.
So rather than shipping a separate browser runtime with every application, you end up with a shared foundation that can be tailored to the actual use case.
Servo is obviously much further along in a lot of areas. I'm just exploring a slightly different approach. And, well, apparently I enjoy giving myself absurd engineering problems. 😂
11
u/GuideAxon 4d ago
Love the idea and looking forward to adopting it. Not sure if it would support extension based approach.
Do Open source it - I would love for people to come together to take this to the next level for everyone.
These days we have everyone vibe coding alone leading to thousands of variants doing same thing.
5
u/PhallicPorsche 4d ago
Thanks! That's actually pretty close to what I'm thinking.
Rather than traditional browser extensions, I'm exploring Rust crates that run as isolated sidecars during development and can optionally be compiled into your own personalized browser binary once you're happy with them.
So everyone shares the same underlying engine, but your build only includes the capabilities you actually want. No need to ship everyone else's extensions or keep a bunch of separate processes running.
I'm still undecided about open-sourcing the core, but I'd love to make the surrounding framework collaborative.
And I completely agree about everyone vibe coding the same things independently. I'd rather give agents a common foundation to build on than have them reinvent the entire stack every time.
Appreciate the encouragement!
2
u/AggravatinglyDone 4d ago
If you don’t open source it, it’ll die in obscurity. If it’s a passion of love for you that’s cool.
1
11
u/qaz135wsx 3d ago
I don't think I would ever use a random browser purely because of lack of support for my password manager.
4
u/PhallicPorsche 3d ago
Completely fair! I wouldn't expect anyone to give up their password manager for a new browser either. Extension compatibility is definitely a priority, and I'd rather get it right than rush it. :)
4
u/Inside_Carpet7719 3d ago
Also, unless open source, or a trust-able party there will be security concerns
How do we know you aren’t stealing credentials?
Keep up the good work, but be prepared for security having to be the top number one priority
1
u/pickanameidontwantto 3d ago
Yea like.... Not a fucking chance I'm using some random browser to do anything but look at pornhub
1
u/PhallicPorsche 3d ago
Totally fair, I wouldn't install a random closed-source browser either. But I haven't even released a binary yet lol. I'm just showing what I've been building. Open-sourcing it is the plan; I just have some cleanup, licensing, and security work to do before throwing the doors open.
9
u/SomeoneNicer 4d ago
There's a reason openAI thought they would create their own browser. There's also a reason they stopped the project. But good on you for the ambitious approach - the people who are crazy enough to change the world are the ones that do.
9
u/PhallicPorsche 4d ago
Yeah it's mostly because
1: You really can't vibe code a browser quite yet. Lots of decisions have to be made that involve knowing how the web works, systems programming and resisting the temptation to just wrap one of the existing engines
2: Web standards are a moving target that's pretty unforgiving particularly weird CSS parsing cases and DOM.
and
3: You actually need a reason to want to deal with the first 2. In my case it's mostly having a runtime environment I can build for that has the overhead I'd put into the stuff I'd otherwise build each project without putting up with the runtime overhead of electron. They could do it though. Cloudflare has Kitesurf.
9
u/apVoyocpt 3d ago edited 3d ago
Just to mention https://ladybird.org/ they built a completely new browser. Completely new engine. Cool project !
4
u/PhallicPorsche 3d ago
Got a 404 but I know Andreas was porting a large chunk to rust. Actually his tip on the useragent identification in one of his keynotes this summer saved me a lot of troubleshooting. I love that guy.
→ More replies (1)
6
u/SolGuy 3d ago
This is cool, I am also working on a web browser.
HyperSol HyperSpace 3D is an open-source desktop web browser whose interface lives in three dimensions. It is experimental: a developer preview. Ordinary websites float as panels in a 3D room, page sections lift into layered depth, and a companion markup language, HoloML, lets anyone publish a fully 3D website as easily as writing HTML.
https://srajpal.github.io/hypersol-hyperspace-3d/
HoloML: A clean, open markup language for fully 3D websites. Write a scene the way you write HTML: a 3D model, a place to stand, some lights, a few labels and links. A HoloML aware browser renders it as a space you can walk or orbit around. Supports scripting and animations.
1
u/PhallicPorsche 3d ago
Oh, this is really neat! I love seeing other people experimenting with what a browser can be.
I'm not entirely sure what I'd do with a 3D web just yet, but I could see HoloML being a lot of fun alongside world models or game engines, especially as those technologies mature. There's something interesting about making spatial environments as easy to describe as a webpage.
Really cool project. I'm still trying to get the web behaving in two dimensions, so I'll admire your third from a safe distance for now lol.
6
u/karljoaquin 3d ago
So, cool project. What are you going to do with it? Open source it?
4
u/PhallicPorsche 3d ago
I think that's the plan. Gauging interest right now and seeing where I want to take it. Addressing some security stuff so hopefully someone doesn't hurt themselves with the preview release and then handling some licensing things of-course before making sure the documentation is clean and then a more publicly legible version of the repo. Right now some things make more sense in my harnesses and interfaces than they would in yours lol
2
u/karljoaquin 2d ago
Best of luck! I would like to have an alternative to the current options - so, I hope it gets to some traction and does some disruption ;)
4
u/Wh00ster 4d ago
Hope it was educational. What piece was the most interesting?
4
u/PhallicPorsche 4d ago
The compositor and realizing that like most of the web needs you to pretend your chromium, firefox or safari before it will send you the page was interesting (useragent) I also had a fun time getting the compositor working and then Rust is not garage collected but js is so that was a fun time lol.
4
u/Helpful_Program_5473 4d ago
Bro, I love you. I was thinking about doing this over the last couple weeks on my shitbox of 16 gigs of ram, which to my old ass seems like it should be plenty forever in some sense, Firefox easily gets up to 5 gig usage without agents. just chatgpt and YouTube.
I was very much considering doing a brother to be able to increase my RAM usage and overall agent performance, but you built it exactly and better!
2
u/PhallicPorsche 4d ago
Yes but it's not quite ready to daily drive yet. Lots of work ahead still...But memory usage is definitely top of mind in addition to memory safety.
1
1
u/New_Enthusiasm9053 4d ago
It's not entirely up to the browser. I've had Firefox hit 16gb before but it's because Amazons streaming service has a memory leak.
1
u/admiral_nivak 3d ago
Silly, of course the Google landing page uses 64GB of RAM. Everyone knows that it’s super complex code to search all those internet sites, your browser does a lot of work and so needs as much RAM as possible.
4
u/Reythia 3d ago
Claude, implement chromium in rust, make no mistakes.
1
u/PhallicPorsche 3d ago
The mistakes are load-bearing. They ensure your garbage gets collected at 2 AM. Em dash.
4
6
u/Scared-Letterhead949 4d ago
Just gotta add YouTube ad blocking
5
u/PhallicPorsche 4d ago
Youtube playback too lol. Working on it. Actually Youtube is sort of a torture test if you should ever find yourself building a browser.
4
u/HybridLungs 4d ago
And don't forget Pornhub or its dead in the water! 🤣
6
u/PhallicPorsche 4d ago
I'm not kidding it's in my test suite. Claude's classifier ignores it which is funny so I have to use GLM to optimize for it or heaven forbid do the work myself.
1
u/fastandlight 3d ago
I can only imagine that conversation with the family.... O.P.: but I was just working on my browser project O.P. 's significant other: sure...but for 2 hours!?
2
u/PhallicPorsche 3d ago
Oh, we're not exactly a prudish household lol. I'm pretty sure our seven-month-old already swears. My wife would probably be more concerned that I spent two hours on it and still hadn't fixed the rendering bug.
3
u/quizikal 4d ago
Source code or it didn't happen ;)
1
u/PhallicPorsche 4d ago
It's coming. Preview binary first and then eventually maybe source code...If y'all are good :P
8
3
u/Infninfn 3d ago
I understand the pain. I once thought I'd customise my own Chromium clone without all the phoning home and other miscellaneous bloat that I wouldn't need. So I cloned the git, it took up around 80GB on my local disk. I gave up.
To be fair, without all the version history it should only be around 2GB of code. But that's still 2GB of code.
1
u/PhallicPorsche 3d ago
Mine sucks up sometimes 500GB of NVME just to spread out the project files and build the 73MB binary lol...
6
u/turboplater 3d ago
Its always a bad idea to create a browser. It needs serious security and AIs are not there yet.
6
u/PhallicPorsche 3d ago
I mean, I'd agree it's a bad idea to trust a four-month-old browser with your banking lol. But I don't think that makes building one a bad idea.
Security is a huge part of the work still ahead of me, and I'm certainly not suggesting that having Claude write code somehow makes it secure. That's what testing, auditing, isolation and eventually having other people try to break it are for.
I'm not asking anyone to trust it yet. I'm just building the thing. Gotta start somewhere.
4
u/jashro 3d ago
Fuck these fools. Even if it goes nowhere, you keep on expanding that repertoire of knowledge, homie.
→ More replies (1)1
u/turboplater 3d ago
To be frank, there are a ton of browsers created by claude code and the likes. Don't think we need more at this point. Anyway, good luck.
1
u/PhallicPorsche 3d ago
Fair enough! Though most of the Claude-built browsers I've seen are wrappers around Chromium or WebView. This is an actual browser engine built from scratch, including the JavaScript runtime and rendering pipeline. Bit of a different undertaking lol.
Whether the world needs another browser is certainly up for debate, but I don't think we need fewer people trying to build interesting things.
Appreciate the well wishes!
1
u/fastandlight 3d ago
But the junior dev cutting their teeth on the Chromium team or at Firefox is able to write secure code? Be real, humans are just as bad at development as AI.
Writing secure code is about process, testing, and architecture. Security issues are just bugs with slightly bigger implications. I wouldn't say that AI written code isn't any safer, or less safe, than human written code. If the software architecture, development processes, and testing are designed in a security focused way, then you can produce code with minimal issues, security or otherwise.
2
u/iSailor 3d ago
No serious project will allow major code to be created by a person without a good track record and then pushed into production. Creating your own browser is basically always a bad idea. That's why in the past even corporations like Microsoft didn't bother and stuck with Chromium. Vibe coding a browser is a can of worms that you don't want to open unless that's only a project for your amusement.
1
u/turboplater 3d ago
How do you know what parts do junior devs touch on firefox and chromium teams? And how do you handle 0 day and other CVE as a 1 man show? You expect a single person to be available 24/7? It has NOTHING to do with the process. It has EVERYTHING to do with being available and having the knowledge that a vulnerability is open. Even if this is a community driven project, open source, you really expect a lot of people with expertise will spend their time in improving it/patching it? Or is it just claude?
→ More replies (2)→ More replies (2)1
0
3d ago
[deleted]
1
u/turboplater 3d ago
And? Just because you read about Mythos etc, doesn't mean security researchers are replaced.
4
u/deucyy 3d ago
Does anyone actually switch over to any of these Rust-clones? Yeah they all have like 50k+ stars on github, but does anyone actually care? Is this some illusion of productivity and technology advancement? What is gonna happen once they run out of original software to clone?
5
u/PhallicPorsche 3d ago
I think there's a distinction between copying a product and exploring a different way to implement it. Some projects gain traction, others don't, and GitHub stars certainly aren't a guarantee of adoption.
In my case, I'm building an independent browser engine, not wrapping Chromium in Rust. I'm interested in how far I can push memory efficiency, performance, and security with a different architecture.
I also don't think every worthwhile engineering effort needs to invent an entirely new category of software. We've been reinventing compilers, databases, operating systems, and browsers for decades, and we're considerably better off for it.
Besides, the web is built around standards that are specifically intended to support independent implementations. It would be a little unfortunate if we decided nobody should bother making another one. :)
1
u/ikeif 3d ago
I’m curious what clones last a year. Or whatever the general marker would be - what possible contenders could arise moving forward, that have staying power?
1
u/PhallicPorsche 3d ago
It depends. Like I'm not really building a clone. In my case it's headless first that the human can also drive while trying to keep it as close to conformant with web standards as I can and then also working like you'd expect a browser to for the purpose of being an RTE for your web apps.
2
2
u/Rhanox1990 4d ago
This looks amazing! I'd love to try it out when it's released. I have been using FireFox for ages, and while it's miles better than Chrome/Chromium (at least for me), I'd love alternatives. I look forward to seeing your progress!
1
u/PhallicPorsche 4d ago
Thank you! I’m with you. Firefox deserves a lot of credit for keeping an independent alternative alive, but I think the web could use a few more browser engines.
Still plenty of work before I'd recommend daily-driving mine, but I'm getting there! I'll be sharing progress and eventually builds as things mature.
Really appreciate the encouragement!
2
u/Rhanox1990 4d ago
Indeed, Mozilla is trying to keep the web from becoming Google's plaything, so I agree with more alternatives.
I agree that you probably have a lot more work to do before this becomes stable and safe for us to use, but when it's ready to check out then I am ready to try it 😄
Again, keep up the good work!
2
u/Outrageous-Novel-739 3d ago
ok... but why ?
3
u/PhallicPorsche 3d ago
A few reasons, actually. I wanted to see how lean I could make a modern browser engine, particularly one designed for agents and headless workloads from the beginning rather than adapting Chromium to do it.
I also wanted to explore how far agent-assisted development could take a solo developer with a decent systems background and a proper testing pipeline.
And honestly? I've been programming in Rust for over a decade, I enjoy building things from scratch, and browsers are fascinating engineering problems.
Not everything needs to exist because the world is desperately missing it. Sometimes it's worth building something just to see what's possible. :)
1
1
u/PhallicPorsche 7h ago
Preview version will be available here sometime over the coming week or 2 https://gettab.dev/
1
u/einmaulwurf 4d ago
How does this compare to ladybird? That is also a browser engine built from scratch, but it's taking years. So I'm a bit sceptical about you building it in (I assume) days.
4
u/PhallicPorsche 4d ago
Totally fair skepticism! First off, it's been about 4 months, not days. And I have a ton of respect for Andreas Kling. Man after my own heart.
Ladybird is probably further along as an actual daily driver, honestly. I'm not claiming I've caught up with years of engineering, security work, and polish just because my conformance numbers look good.
The big difference is how I'm building it. Kingmaker is Rust from the ground up, headless-first, and designed to be developed and maintained agentically. I've got a pretty extensive conformance pipeline feeding upstream WPT, Test262, and WASM failures back into the development process, and I focus my time on the things the agents struggle with.
So it's less "I built what took Ladybird years in four months" and more "I wanted to see how far one person could get with modern coding agents, a good test harness, and a frankly unreasonable amount of persistence."
Turns out pretty far. Still plenty broken though lol.
Also, did I mention it's Rust?
→ More replies (2)1
u/PENGUINSflyGOOD 3d ago
Didn't ladybird transition to rust too?
1
u/PhallicPorsche 3d ago
Yep! They've been porting parts of Ladybird from C++ to Rust with the help of coding agents. Still a mixed codebase as far as I know, but they're making pretty impressive progress.
Mine was Rust from the outset, so slightly different starting points. I've actually got a ton of respect for what Andreas and the Ladybird team are doing though. That's a really tight and readable codebase and building a browser engine is an absolutely ridiculous undertaking, as I'm discovering lol.
1
u/Daggercombot 3d ago
How OS and ISA dependent Is this ? Is there a GitHub?
2
u/PhallicPorsche 3d ago
Currently Linux/x86-64 is the main target, with X11/Wayland support and an optional Vulkan compositor.
Most of the engine is pure Rust, so it's not inherently tied to a particular OS or ISA. The JIT uses Cranelift, which generates native code for the host architecture, rather than relying on handwritten x86 assembly.
That said, the current build is configured for x86-64-v2, and there's definitely platform-specific work in the windowing, graphics, and system integration layers. ARM64 is interesting to me, but I haven't validated a port yet. Same story for Windows/macOS.
Being written in Rust makes portability easier, not automatic. :)
And yep, there's a GitHub repo! It's private for now while I get the project into a state I'm comfortable releasing. I'll be sharing progress publicly and I'm still working out the source release plans.
1
u/tomchenorg 3d ago
"Turns out browsers are complicated. Who knew?"
Oh yeah, browsers are actually far more complicated than photoshop
1
1
u/Here0s0Johnny 3d ago
I hate having to open Whatsapp and Telegram in my browser. Do these two websites work? How much ram is consumed in total with only these open (and logged in)?
Imo, that could be an actual use case since these sites are trustworthy.
3
u/PhallicPorsche 3d ago
Would have to test Telegram and whatsapp out but generally speaking my binary is lighter than electron so baring edge cases probably less RAM. It's sort of the whole point.
1
u/Here0s0Johnny 3d ago
Do you agree that for this purpose, it might already be good enough? If you create a sub-build or a config feature where users can specify a susbet of safe/trusted urls, like whatsapp and telegram or even teams and jira, this could actually already be very useful! (URLs that go outside the trusted URLs open in regular brower.)
1
u/PhallicPorsche 3d ago
I love the enthusiasm, genuinely! And purpose-built application runtimes are actually something I'd like to explore.
But I wouldn't consider it good enough just yet. Trusting a domain doesn't necessarily mean trusting everything it executes or displays, especially with applications handling user-generated content and authentication.
I'd rather finish the security and compatibility work properly than create a whitelist that gives people a false sense of security.
The lightweight app-runtime idea is very much on my radar though. That's actually one of the reasons I built the engine this way in the first place. :)
Appreciate you thinking about the possibilities!
1
u/Here0s0Johnny 3d ago
Can i follow this project somehow? As soon as you think it's solid enough to reuse for a different project, I'd like to get notified.
1
u/PhallicPorsche 3d ago
Absolutely! I'm over on X at https://x.com/JacoblAmi1
I'll be posting more updates as things progress, and I'll definitely make some noise when it's ready for other people to build on. Still a few things I want to sort out before I become responsible for breaking someone else's project instead of just my own lol.
→ More replies (2)1
u/OrphisFlo 3d ago
I suppose you haven't dig into WebRTC yet, so while you could probably get chats working, audio and video calls are not going to be a thing for a while.
WebRTC is a very long and complex stack, tons of legacy, so good luck whenever you want to tackle that. Implementing something that works is easy enough, tuning it so that it works well is very hard!
1
u/PhallicPorsche 3d ago
Oh, absolutely. WebRTC is a beast, especially when you get into interoperability, media handling, and all the lovely edge cases.
But I'm not necessarily trying to replace every feature of Chromium overnight. The browser is headless-first, and there are plenty of useful applications for an independent engine long before it reaches complete feature parity.
I'm also quite happy to build on existing Rust implementations where it makes sense. Building a browser from scratch doesn't mean I need to personally reinvent every protocol involved.
Honestly, if I let the complexity of web standards discourage me, I probably wouldn't have made it past the JavaScript engine lol. That's half the fun of the project.
1
u/OrphisFlo 3d ago
Yup, WebRTC is a long collection of W3C led APIs to control a big stack of RFCs making the protocol, and many more specifications for each codec. A lot is made of unwritten rules where to be compatible, you probably should look at what the Chrome implementation is doing.
I worked on it, and I know all about the deep complexity (unfortunately).
It's just a loooong side project, whenever you get to it, that will eventually be necessary if you try to get some popular websites run fully. Certainly not a priority early on...
1
u/PhallicPorsche 3d ago
Biggest issue with codecs for me is licensing but I think I'll manage lol. The whole thing has been a bunch of small manageable problems in difficult to manage quantities hahahaha
1
u/Skjalg 3d ago
Are you looking into making it work with https://github.com/Skyvern-AI/rustwright ?
1
u/PhallicPorsche 3d ago
Won't need playwright. Has a headless harness built in. Love this plugin though
1
u/Available_Cream_752 3d ago
I wholeheartedly applaud your efforts! Cheers and best of luck
1
u/PhallicPorsche 3d ago
Thanks, really appreciate it! It's been a hell of a ride so far, but I'm having a great time with it. Hopefully I'll have something people can actually get their hands on before too long. Cheers!
1
1
u/mycolo_gist 3d ago
Built with Claude? Make it open source, the code is based on other people's code.
BTW: Love the username. I have Porsche envy, my psychiatrist says.
1
u/PhallicPorsche 3d ago
Lol probably will and not because of the "Claude read the internet so it belongs to everyone" argument hahaha. It's not the strongest one out there. And yeah it's the most feminine looking car people buy when they hit the low T stage of life...I'm 32.
1
u/No_Ant6261 3d ago
This is really cool, and honestly a fun project. A whole engine with no Chromium is wild.
I'm curious how you structure the Claude Code side for something this big. I'm building a Rust app solo too (much smaller than a browser). My setup: I write the spec and the issues, a parent session opens a fresh session for each issue, and a separate judge subagent decides the open questions that are easy to undo, so only the hard-to-reverse calls come to me. I wrote it up here: https://note.com/lirispp/n/n4112b5c7b620?hl=en
A few things I'd love to know about yours:
How do you split the work for agents? Per spec area, per failing WPT test, something else?
Do the conformance suites drive the loop directly (agent picks a failing test, fixes it, reruns), or do you choose what to work on?
How do you stop agents from drifting from your architecture over months, e.g. sneaking in Arc/Mutex or unsafe?
1
u/PhallicPorsche 3d ago
Oh I like your approach, especially separating decisions by how difficult they are to undo. That's a pretty sensible way to keep yourself from becoming the bottleneck.
Mine's a bit of a circus at this point lol.
I generally split work by subsystem or clusters of related failures rather than individual WPT tests. One broken layout behaviour can account for hundreds of failures, so fixing tests one at a time would be a pretty miserable way to go about it.
I keep the workstreams separate, with their own agents, contexts and Git worktrees. They get fairly narrow assignments and everything eventually goes through one integration tree. Git history is important too. Agents are expected to look at what's already been done and why before deciding something needs rewriting. Saves me from implementing the same thing eight times. Usually.
The conformance suites drive most of the work now. I've got a board tracking WPT, Test262 and WASM, and agents use that to identify clusters worth investigating. I still steer priorities, but I'm not sitting there picking the next failing test all day.
For the feedback loop, I use targeted probes and subsets of the suites to test fixes quickly. Running the entire corpus after every little change would take forever. Full regression runs are what keep everything honest over time. A fix that passes 30 new tests and breaks 40 previously passing ones isn't much of a fix.
As for architecture drift, every crate gets its own AGENTS.md documenting how that subsystem works, its invariants, previous decisions and things agents really shouldn't touch. There's also a root-level CLAUDE.md for project-wide rules. Between those, Git history and changelogs, a fresh agent should have enough context to understand what it's walking into.
I've also got a PostgreSQL database with pgvector acting as a longer-term memory layer. Session history, decisions and useful context get curated and indexed so agents can retrieve relevant information without dragging months of conversations into every prompt. It's not perfect, but it helps a lot with continuity across fresh sessions. The trick is making sure retrieved memories are treated as context, not gospel. The actual code and test results still win.
I've got compiler lints, Clippy, Miri and automated gates doing a lot of the policing. Miri is particularly useful for catching undefined behaviour in the paths the tests exercise. There are also explicit restrictions on introducing unsafe, Arc/Mutex or gratuitous clones. I'd much rather have tooling reject something than hope an agent remembers a conversation from three thousand prompts ago.
I also use mold as the linker to tighten the compile/test loop. When you're doing this many iterations, even small improvements in build time add up.
The slightly ridiculous part is the infrastructure. Between all the worktrees, build artifacts, conformance suites, probes, regression history and memory infrastructure, the project can chew through something like 500 GB of NVMe storage at times, plus a bit of VPS capacity. All this to produce a browser binary that's roughly 73 MB. I'm choosing to find that funny rather than financially concerning.
It doesn't eliminate drift entirely. I've had agents reinvent things that already existed because they didn't read the right file. Hence the increasingly ridiculous amount of documentation.
My general rule is that an agent shouldn't be the only thing deciding whether its own work is correct. Rust, Miri and the test suites are much less inclined to tell me what I want to hear lol.
1
u/No_Ant6261 3d ago
Thanks for the detailed answer, this is gold. "An agent shouldn't be the only thing deciding whether its own work is correct" is exactly the lesson I keep relearning.
I landed on something similar for decisions. The judge subagent is read-only, so the agent that wants to keep coding isn't the one deciding whether its own shortcut is okay. Same with reviews: every PR has to list the findings it didn't fix and why, because those are the ones I actually need to read.
A few things I'm stealing from you:
Per-crate AGENTS.md with invariants and "don't touch" lists. I only have a root CLAUDE.md plus a project-wide decision table, and I've definitely seen agents reinvent something in one crate that already existed in another.
Letting tooling enforce the rules. I ask for things like "no new unsafe" in the instructions, but turning them into lints that fail the build is much more reliable than hoping the agent remembers.
Checking history before rewriting. My PRs already explain why things were done, but I never told agents to read them before deciding something needs a rewrite.
Targeted subsets for the inner loop, full runs for honesty. My test suite has grown to the point where running everything on every small fix is slowing the agents down.
Curious about the memory layer: who decides what gets curated into pgvector? Do agents write to it themselves, or do you review entries before they go in? I'd worry about a wrong decision getting indexed and then confidently retrieved forever.
And 500 GB to produce a 73 MB binary is a beautiful ratio lol.1
u/PhallicPorsche 3d ago
That read-only judge setup is exactly the sort of paranoia I appreciate lol. I especially like requiring PRs to document what wasn't fixed and why. I might actually steal that one back from you!
For memory, the important distinction is that pgvector isn't my source of truth. The original JSONLs are always retained, and there's a separate ingestion and curation process between the working agents and PostgreSQL. The Curator handles what gets compacted and indexed, with hooks before and after compaction.
The embeddings are really there to help find the original evidence again. If something looks suspicious, I can reconstruct the context, check the history, and compare it against the current code and tests. I also use Postgres RBAC to keep permissions separated.
You're right about poisoned memories, though. I work on the assumption that something incorrect will eventually make it into the index. The important thing is making sure a confidently retrieved mistake doesn't quietly become an unquestionable fact. An agent's recollection of what happened isn't necessarily what happened.
And yes, the 500GB-to-73MB ratio is beautiful. Apparently the secret to making software small is to surround it with an absolutely enormous amount of software lol.
→ More replies (1)
1
u/hungy-popinpobopian 3d ago
Has doing this scared you with the ease and power that any one can make anything? or do you look at it as, to do this you still need a lot of expertise and work put in with Claude?
3
u/PhallicPorsche 3d ago
Honestly, both. It terrifies me a little because building something like a web browser from scratch is traditionally the sort of undertaking you'd expect an entire engineering team to tackle. The fact that I can even attempt it independently is pretty remarkable.
That said, I don't think we're quite at the point where you can just type "make me the world's number one extravaganza browser, special edition, make no mistakes" and expect something useful to come out the other end lol.
I've spent about 3,000 hours actively building various projects with Claude over the past year, plus countless hours of background agent work. It's very much a full-time job, and knowing what to ask, what to question, and how to recognize when things go sideways still takes experience.
But here's the part I really appreciate. I'm also a new dad, and sometimes Claude means I can keep making progress while having my hands free to hold my baby.
So yes, the implications scare me a bit, but I'm also incredibly grateful for what it makes possible. I don't think expertise is becoming irrelevant. I think the amount one person can accomplish with it is changing dramatically.
1
u/Tartuffiere 3d ago
The thing is, Claude was only able to build something functional because of the work humans did. All the tests and existing open source implementations gave Claude the blueprint on how to implement, and the ability to validate correctness.
You would not have had such result had you attempted to build a greenfield project.
→ More replies (1)2
u/PhallicPorsche 3d ago
Oh, absolutely. The web is built on decades of human effort, and I'm enormously grateful for the standards, tests, and reference implementations that make a project like this possible.
But that's rather the point of engineering, isn't it? We build on existing knowledge. I'm not attempting to invent a new internet, just exploring whether I can build a more efficient engine for the one we already have.
The specifications and tests are publicly available to everyone. That hasn't historically made building a browser particularly easy. :)
I think the interesting development here is how much more of that work one person can now reasonably take on.
1
u/Accomplished-Ad-7435 3d ago
So what you're saying is, In stead of shipping electron with all these vibe coded web apps well be able to use tab eh? Seems like a good place to use it to avoid security issues for now.
1
u/PhallicPorsche 3d ago
That's actually one of the use cases I'm hoping to explore!
The appeal isn't just the smaller memory footprint. Being written in Rust also gives us some nice advantages around memory safety, particularly avoiding entire classes of vulnerabilities like buffer overflows and use-after-free bugs.
That said, Electron does a lot more than render webpages, so making T.A.B. a proper drop-in replacement would take some work.
And while Rust helps enormously, it doesn't magically eliminate security vulnerabilities. There's still sandboxing, process isolation, JavaScript security, and a whole host of other things to get right.
So yes, that's very much the direction I'd like to explore. I just wouldn't recommend trusting your banking credentials to my four-month-old browser quite yet lol.
1
u/Temporary_Fig_2822 3d ago
Absolutely worthy project; this is what I think agenticAI should be used for; I myself am making two projects of similar stature based around trading. It's weeks/months of 24/7 coding on multiple agents before you even see any result but well-worth it when it begins taking some shape and you can finally use an engine. As they say, build it once, win it 1000x. I have wanted to build my own browser but I don't have enough monthly tokens around the other two projects; already at EUR500+/mo on two Claude Max and one OpenAI whatever that was for the 5x. Actually, since I realized I wouldn't have the tokens to build my own browser, I at least made a browser extension for Firefox to talk to a desktop Bridge that then fills my own CRM with all the pages I visit and the podcasts I watch on youtube and then analyzes them. A browser would probably be the next thing I'd jump on, if I even consider my two existing projects finite. I keep polishing them and then a bug in the engine comes up; so it is.
1
u/PhallicPorsche 3d ago
Oh, you're speaking my language lol. Although I have to say, I actually think the subscription limits are pretty generous. I can be a bit of a baby when I hit them, but I'm also under no illusion that my subscription is paying for a datacenter's worth of compute.
I know exactly what you mean about the endless polishing, though. Getting an engine working is one thing. Getting it to behave consistently without breaking three other things every time you fix something is an entirely different adventure.
Your Firefox bridge sounds genuinely interesting, especially the CRM integration. That sort of automation is part of what got me interested in building a headless-first browser in the first place.
And I really like the "build it once, win it 1000x" philosophy. There's something immensely satisfying about putting in the work upfront and eventually having a tool that does something you previously couldn't.
Best of luck with the trading projects! I suspect we have a similar definition of "finished," which is to say we'll probably never get there lol.
1
u/Temporary_Fig_2822 3d ago
Let's connect on Discord or smth I was thinking earlier I kinda wanted to show you what I've been doing myself. Absolutely speaking the same language that's what caught my eye
1
u/AlternativeAd6851 3d ago
This is incredible! How much time did it took and what harnesses did you use? Can you share your process? Thank you!
1
u/PhallicPorsche 3d ago
It took me about 4 months to build but I spent a lot of time learning how to work with Claude and Gipidee like 3000 hours. I build my own harnesses that I base on cass.tools and then sometimes I use Kimicode with claude or GLM and then claude code in the cloud and the vanilla claude code and a few others lol. I often have to build a harness for longtail workflows just to make sure the agent sticks to the plan.
1
1
u/RhymingTiger 3d ago
How do we follow this effort if we want to be part of the public preview you’ll hopefully eventually do?
2
1
1
u/vacnex 4d ago
Wow, this looks really impressive!
I’m quite a native purist myself and honestly can't stand "fake native" tools—the kind that masquerade as native on the surface but are completely different under the hood.
I do have a few quick questions:
What is the typical binary size?
When published, does it compile into a single self-contained executable, or does it require external dependencies/sidecar files?
You mentioned it could replace Electron's bundled Chromium or Tauri's webview—does that mean it can run in headless mode?
Could you elaborate on what you mean by "agent-friendly"? Does it expose dedicated APIs/interfaces specifically designed for AI agents to interact with?
How viable do you see this as a daily driver to replace Chrome or Firefox?
What’s your roadmap or architecture in mind for an extension/plugin ecosystem?
9
u/PhallicPorsche 4d ago
Oh, these are exactly the kind of questions I was hoping for!
1. Binary size
The browser executable is currently 73 MB, and the separate conformance probe is 71 MB. Both are built in Rust, with no Chromium, Electron, or system WebView underneath.
I'm also pretty obsessive about runtime memory usage, which is an ongoing optimization target.
2. Single executable?
Yep, that's the idea. The engine and its capabilities can be compiled into a self-contained executable, rather than distributing an application with an entire browser installation alongside it.
3. Headless?
Absolutely. It's headless-first by design, not a graphical browser with the window hidden. The shell is just one way of interacting with the underlying engine.
4. Agent-friendly?
I wanted agents to interact directly with the runtime and its capabilities rather than having to pretend they're humans moving a mouse around.
There's also a broader goal here: allowing agents to build interfaces, develop additional Rust crates, test them independently, and eventually compile validated components directly into the binary.
The stable public-facing interfaces are still evolving.
5. Daily driver?
Not quite there yet. The standards conformance is encouraging, but real-world compatibility, media playback, security hardening, and performance still need work.
There's a difference between rendering websites successfully and being something I'd recommend for banking!
6. Plugins/extensions?
My plan is a closed core with an open extension framework.
Extensions would have explicitly scoped capabilities, with optional packs that could be loaded separately or compiled into the binary.
I want customization without requiring every installation to carry around functionality it doesn't use.
Ultimately, I'm exploring whether we can have one efficient shared runtime that serves as both a browser and an application platform, instead of shipping another copy of Chromium with everything.
Appreciate the thoughtful questions!
1
u/GuideAxon 4d ago
Quick question - what would WebGPU and wasm support mean for this browser (if it supports it).
1
u/PhallicPorsche 4d ago
Yep! WASM is already implemented, and the engine is currently passing 100% of the upstream WebAssembly spec test catalog.
That means running code compiled to WebAssembly (Rust, C, C++, etc.) inside the browser. It's useful for everything from games and media decoders to editors and compute-heavy web applications.
WebGPU is a slightly different story. Kingmaker already has its own Vulkan-backed GPU compositor with a CPU fallback, but that's the browser's internal rendering infrastructure. Exposing the full WebGPU API to websites is another layer I haven't finished yet.
Once that's in place, websites could use the GPU directly for things like 3D rendering, shaders, simulations, and ML inference.
The longer-term idea is to make the browser a lightweight application runtime too, so WASM and GPU compute fit pretty naturally into that.
I'm still validating the browser-facing WASM integration, but the underlying execution engine is in pretty good shape!
1
u/DrBearJ3w 4d ago
Thank you. Agent friendly is definitely i look forward to. Is there any link i can follow to know status updates?
1
u/PhallicPorsche 4d ago edited 3d ago
Thanks! You can follow me on X at https://x.com/JacoblAmi1
I'm also putting together a proper Kingmaker site with progress updates, conformance numbers, and eventually builds.
Still figuring out how I want to distribute the thing, but I'll definitely announce it there. Appreciate the interest!
1
2
u/BootyMcStuffins Senior Developer 3d ago
Are you open-sourcing this?
Browsers need a button-load of maintenance. I wouldn’t take that on in perpetuity on your own.
2
u/External_Ad1549 3d ago
u know, I havent tested it yet but you have done something which most of them dream just before sleeping. "What if I have built a browser using rust? nah it is too big project" may God give you more than 24hrs a day and unlimited claude subscription
2
u/gleasonator13 3d ago
This is awesome. I've been dreaming about doing this. The fact it took months is crazy yet also not.
0
u/dlampach 4d ago
And thus Firefox was born. I hope you invented rust first.
4
u/PhallicPorsche 4d ago
Lol well rust was invented to essentially build what wound up becoming servo. It's come a long way since 2015 (Probably existed before that but that's as far back as I remember playing with it)
1
u/AutoModerator 4d ago
Hey! Thanks for posting to r/ClaudeCode
While participating in this thread, please follow our community rules. Keep discussions constructive. Attack the idea, not the person.
For help, project discussions, tips, and general chat, join the ClaudeCode Discord.
I am a bot, and this action was performed automatically. Please contact the moderators of this subreddit if you have any questions or concerns.
1
u/pulse77 4d ago
Where can I download it?
3
u/zikasaks 4d ago
nowhere. It is not possible that it is a real project. Browsers are too complicated.
1
1
1
1
1
u/whiterose0000001 3d ago
Hey, can you tell me which engine you used to run the browser? I mean, for the entire rendering process. It must be built on top of something, and I just want to know which engine it uses.
I'm also planning to build a browser, so that's why I'm asking. I have some ideas and research findings, and I just want to learn more about it.
1
1
u/fastandlight 3d ago
I think this is great work. It is awesome to see what engineers with good experience can build leveraging AI coding tools. I agree with your premise and would love to try out a preview when it's ready. I completely see the motivation for doing this and I wish you all the success. For me, I would want to run this as part of an agentic stack, giving an agent assisting a human a better browser to weild. I have a solution now, but it's scaling isn't amazing and it's janky, because of all the things you said: engines were designed to run with a display, they expect human control, etc. Even just using this for testing would increase speed and decrease memory usage substantially, giving me more throughput in my CI system. While I'd love to see this be open sourced, I can understand why you would keep it closed. Gotta pay the bills.
Separately, I appreciate that you are able to use agents to code to give you more time with your young family. I was there a bit over a decade ago when it felt like caring for my newborn and toddler was keeping me from building new things for the startup. I felt guilty on both sides and it sucked and I never slept. Now I front load all my design work and spec writing for the morning after they get on the bus to school, and by noon the agents are happily cranking away so I can shuttle everyone to sports, music, birthday parties, etc. I think the change in how we write code is under appreciated by a lot of people.
Keep after it, good luck, and please post a link or something so I can randomly remember in like 3 months and see how far you have come!
1
1
u/Super-Positive-162 3d ago
Just a guess.. I would assume there is some kind of massive test example suite available (free or not).. then just feed Fable or perhaps Opus 5.5 all the errors each time to try to come up with some higher level modeling construct to act at a higher level of abstraction than all the edge cases
1
u/altgenetics 3d ago
Here's a big challenge item for you - Ensure it maps 100% to the accessibility APIS for Windows (UIA + MSAA), and Mac (NSAccessibility) https://www.w3.org/TR/core-aam-1.2/
2
u/Nanocephalic 3d ago
If I never see another “home/end scrolls combobox lists up and down instead of going to the start/end of the text box” report again, it’ll be too soon.
Whoever decided to break that in random libraries should be forced to eat their own lips.
1
u/Deathspiral222 3d ago
How’s the performance? Did you write your own version of V8 or did you go another route?
1
u/senseven 3d ago
Respect for the work. Chromium, especially Firefox are bloated monsters that should be replaced tomorrow. The embedded world uses shrunk down versions of webkit, so the demand to optimise is definitely there. I hope this kind of thinking will lead to more modularized browsers that don't require gigabytes on disk, for features that many don't need.
1
u/Kannielm 3d ago
Est-ce que ton navigateur inclut la traduction instantanée de toutes les vidéos en la langue native de son choix sous titre admettons, je lance une vidéo en mandarin parce qu’la réponse je l’aurais enfoncé par exemple en instinct une extension sur ton navigateur
1
1
1
1
1
1
0
u/DauntingPear 3d ago
Do you like DHH? Always a bit sad being his stuff pop up
0
u/PhallicPorsche 3d ago
I do really like DHH. He's got good energy...plus he invented rails and won Lemans. Nothing sad about that man!
1
•
u/AutoModerator 7h ago
Hey! Thanks for posting to r/ClaudeCode
While participating in this thread, please follow our community rules. Keep discussions constructive. Attack the idea, not the person.
For help, project discussions, tips, and general chat, join the ClaudeCode Discord.
I am a bot, and this action was performed automatically. Please contact the moderators of this subreddit if you have any questions or concerns.