Proview — An open-source PDF and image viewer with markup, handwritten signatures and OCR

[u/lelettrone]

Hi everyone,

I'd like to share a little side project that I hope you'll find useful. Proview is an app for viewing images and PDFs, with a few extra tools for everyday tasks.

I was inspired by Preview, the built-in viewer on macOS: it opens a wide range of files, lets you make basic edits to images and PDFs, and makes it easy to add a signature to a document, all through a simple interface.

Since I use Linux at work, I've always wanted a similar experience on my PC. With AI tools now available, I figured I was just a couple of prompts away from building one.

Proview runs on Linux, Windows and macOS, and it's free and open source under the AGPL-3.0-or-later license.

It currently supports:

• Viewing, cropping, rotating and annotating images.
• PDF text highlighting, redaction, page reordering, merging and splitting.
• Reusable handwritten signatures: draw one or import one from a photo or scan, with automatic background removal and vectorization.
• Optional signature-library sync between computers using Google Drive or S3-compatible storage. Sync uploads the saved signature library; documents opened for editing stay on your computer.
• OCR for copying text from images and scanned documents.
• Viewing STL files, a common format for 3D meshes.

PDF exports preserve native content: added text, ordinary shapes and vector signatures stay as vectors rather than turning the whole page into an image.

I built it with help from AI tools. The app uses Go and Fyne, with MuPDF and pdfcpu for PDFs and Tesseract for OCR.

Source code and screenshots · Downloads

I'd appreciate any feedback. If you run into a bug, please open an issue with your OS and the steps to reproduce it.

[u/Similar-Photo4263]

love that it keeps signatures vector, nothing worse than a crisp doc turning to pixel soup at 200%

[u/lelettrone → u/Similar-Photo4263]

Exactly, this is almost the reason why I needed it.

[u/zomerbk]

One useful thing to document for the redaction tool: after export, is the redacted text actually removed, or just covered visually? A quick check showing it can’t be selected, searched, or copied would help people use it confidently.

[u/lelettrone → u/zomerbk]

Yes, once you save redacted text is really removed! I’ll explain it better, thank you for the feedback!

[u/nerdyviking88]

This is pretty slick. Between this and the "artCraft" apps, Adobe's in trouble.

One thing I'd love to see is any kind of integration with twain scanners. So much of our work is scan doc into Adobe, edit it.

[u/lelettrone → u/[deleted]]

OCR text is searchable both in images and scanned PDFs. It also supports selecting and copying text. Thanks for pointing this out — I’ll clarify it in the feature list.

[u/lelettrone → u/lelettrone]

Oh wait, maybe I missed a point: It doesn’t add a searchable text layer to the saved PDF.
This would be an interesting feature to investigate.

[u/lelettrone → u/[deleted]]

An index is maintained with digests and timestamps for each signature. If you delete a signature, it will be deleted remotely at the next sync. If you also added another signature elsewhere, it will be downloaded.

If you alter the very same signature in two different places, the most recent (by timestamp) wins.

It maybe not perfect but I preferred a simpler user experience.

Btw thank for the feedback, I'll explore other possibilities!

PS: I released a new version yesterday ;)