Firefox's built-in PDF.js viewer is one of the most underrated tools in the browser world. Mozilla put real effort in: highlight, draw, add text, sign. For light editing, Firefox alone covers more than people realise.
For heavier editing — changing existing text, conversion, compression — Flint picks up where PDF.js stops.
What PDF.js can do
Open a PDF in Firefox. Toolbar gives you: highlight (multiple colours), draw (mouse, touch, stylus), add text overlays, sign with mouse or pen. Save back to file. For light annotation and signing, Firefox doesn't need any other tool.
What it doesn't do: edit existing text in the PDF. That's Flint's job.
Pairing PDF.js with Flint
Use PDF.js for annotation and quick signing. Open Flint in another tab for text edits, conversion, merging, compression. Both run in Firefox, no extensions, no install.
For users committed to Firefox, this combination matches what Chrome plus Flint or Safari plus Flint offers on other browsers.
Firefox-specific considerations
Firefox doesn't auto-update PDF.js — it's bundled with the browser. Keeping Firefox itself updated ensures the PDF features are current. Flint, being a web app, always has the latest features regardless of Firefox version (within reason).
FAQ
Is Firefox's PDF viewer better than Chrome's?
For editing, yes — Firefox PDF.js has annotation tools Chrome lacks built-in. For viewing, both are excellent. Comparison matters mostly for users who don't want to install separate tools.
Will Firefox PDF edits save correctly?
Yes. PDF.js saves annotations as part of the PDF. Open in any other reader (Acrobat, Edge, Preview) and the annotations show.
Do I need a Firefox add-on for PDF editing?
No. PDF.js is built in, and Flint runs as a web app without add-ons. Most 'Firefox PDF editor' add-ons are redundant.
Firefox handles annotation. Flint handles real edits. Same browser, full toolkit.