The free, open-source PDF editor that edits the text inside your PDF — entirely in your browser.
No uploads · No accounts · No watermarks · No page limits · No catch
⭐ If this saves you an Adobe subscription, a star helps others find it.
Real recording: the tagline above is retyped live — the original text operators are rewritten in the file, not overlaid.
Most "free" PDF editors work the same way: upload your contract or your ID to somebody's server, edit three pages, then get hit with a paywall, a watermark, a page cap, or a sign-up screen the moment you press Save. (The honest exceptions are self-hosted tools — but those make you run the infrastructure.) Desktop editors that genuinely modify existing text cost a subscription.
PDF Studio runs 100% in your browser. Your files are opened, edited, and saved on your own machine — there is no server to upload to. And unlike most free editors, it doesn't fake the editing: the Edit tool rewrites the page's content stream itself. The original text is deleted from the file and your replacement is written in as real vector text. Not an overlay. Not a text box on top. The old bytes are gone.
Try it in 30 seconds: open the live app, drop in any PDF, press E, click any line of existing text, retype it.
| ✏️ True text editing | Click any line — or any table cell — and retype it. Exports as real vector text, searchable and print-crisp. |
| 📝 Forms | Fill real AcroForms (text, checkboxes, radios, dropdowns), then flatten them so nobody can change your answers. |
| 🖋️ Sign & annotate | Signature pad, highlight, pen, arrows, shapes, sticky notes, image stamps — all real vector content. |
| 🖤 Redaction | True redaction — covered text is deleted from the file at export, not painted over. (Whiteout covers are visual-only; use redaction for sensitive data.) |
| 🔠 OCR | Scanned pages become editable text via on-device Tesseract (EN/ES/FR/DE). No upload, ever. |
| 🤖 On-device AI | Ask questions about your document; a real LLM runs in your browser via WebAssembly. Your data never leaves. |
| ⚖️ Revision diff | Drop in two versions, get a line-by-line diff. Did the payment terms change? Now you know. |
| 📄 Pages | Reorder, rotate, merge, split, duplicate, delete. Stamp page numbers, watermarks, headers & footers at export. |
| 📱 Anywhere | PWA — installs to your phone or desktop, works offline, autosaves and resumes your session. |
Screenshots — every claim above, captured from the running app
Verified against public pricing/feature pages on 2026-09-27.
| PDF Studio | Adobe Acrobat | Smallpdf | Sejda | Stirling PDF | |
|---|---|---|---|---|---|
| Price | Free, MIT open source | ~$19.99/user/mo | $10–15/mo | ~$7.50/mo | Free (self-hosted) |
| True in-place text editing | Yes | Yes (paid) | Yes (paid) | Yes | Partial |
| Your document leaves your device | Never | Uploads to Adobe | Uploads to Smallpdf | Uploads (web) | Never (your server) |
| Daily / task caps | None | Paid tier | ~2 tasks/day | 3 tasks/day | None |
| Watermark on free output | None | — | Reported on some tools | None reported | None |
| Burned-in redaction | Yes | Yes (paid) | Paid | Whiteout-style | Yes |
| OCR | Yes, on-device | Paid | Paid | Capped | Yes |
| Revision diff | Yes | Yes (paid) | Paid | No | — |
| On-device AI Q&A | Yes | Paid add-on | Limited | No | No |
| Zero-setup (no install, no server) | Yes | — | Yes | Yes | No (Docker) |
The short version: incumbents upload your files and meter your work. Self-hosted tools make you run infrastructure. PDF Studio is the zero-setup option that keeps the full feature list — free, no caps, no uploads.
| Question | Answer |
|---|---|
| Where do my files go? | Nowhere. There is no upload endpoint. Open devtools while you edit: your document bytes never leave the machine. |
| Is any of my data collected? | No. No accounts, no analytics on your documents. Sessions autosave locally in your browser. |
| What does download? | The app itself, plus optional public AI/OCR model weights (cached after first fetch). Your documents never transit the network. |
| Can I air-gap it? | Yes. Serve dist/ on an internal network and point the model loaders at internal mirrors. |
git clone https://github.com/Kayforkind/NavigatorsLab-PDF-Studio
cd NavigatorsLab-PDF-Studio
npm install
npm run dev # http://localhost:5199
npm test # 42 passing tests
npm run build # → dist/ (relative base: works at domain root, subpath, or CDN)Stack: TypeScript · React 19 · Vite · pdf.js (render) · pdf-lib (write) · Tesseract.js (OCR) · WebLLM (AI) · vite-plugin-pwa. Zero backend.
The interesting engineering: every mark lives in the page's PDF user space — the on-screen overlay and the exporter share the same CropBox-aware transform math (src/lib/viewport.ts), pinned in tests against pdf.js's own PageViewport, including offset MediaBox/CropBox origins that break most home-grown editors. Text edits go through a content-stream tokenizer: the original glyphs' show-text operators are deleted and replacements are written back with TJ kerning reproducing the original spacing. Tesseract, pdf.js workers, and WASM all run under a strict Content Security Policy with zero network calls for document data.
Test suite (42): document model ops & undo semantics · viewport parity with pdf.js at 0/90/180/270° · export round-trips re-parsed with pdf.js · LCS diff engine · content-stream tokenizer + deep text-rewrite/vector-redaction round-trips · table-cell hit splitting.
Good first issues are labeled good first issue — see CONTRIBUTING.md.
Kazim Raza (@Kayforkind) — creator of PDF Studio and founder of NavigatorsLab.
- Is it really free? What's the catch? — Free, MIT-licensed, no catch. No accounts, no watermarks, no caps, no "pro" tier. Fork it, self-host it, ship it.
- How is this different from other free PDF editors? — They let you annotate (text boxes over content). PDF Studio rewrites the content stream: original text operators are deleted from the file, replacements written in as real vector text.
- Honest limits? — Text editing needs a text layer (flat scans go through the OCR tool). Replacement text uses Helvetica metrics — near-identical, not glyph-perfect, on exotic embedded fonts. The on-device AI runs small models (0.5B–1B): great at summarizing your document, not a frontier model.
MIT — free for personal, commercial, and everything in between. That's the whole point: LICENSE.
Free. Open source. Private by architecture, not by policy.