The free PDF editor that edits your files without ever seeing them.
▶ Try it live — no install, no upload, no account
🎬 Watch the redaction exposé (55 sec) — a black-box "redaction" leaves your text selectable underneath. Ours deletes it for real.
Real recording: the tagline above is retyped live — the original text operators are rewritten in the file, not overlaid.
In your browser, nothing to install: navigatorslab.com/pdf-studio
Self host with Docker, one command:
docker run -p 8080:80 ghcr.io/kayforkind/navigatorslab-pdf-studio:latest
# → http://localhost:8080CLI, from source (three commands):
git clone https://github.com/Kayforkind/NavigatorsLab-PDF-Studio && cd NavigatorsLab-PDF-Studio
npm install && npm run build:packages
npx pdfstudio info contract.pdfMost "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
The full editor — free forever, private by design
Edit hints — every line of the original text is a clickable target
Annotate — underline tool with color and opacity controls
True redaction — covered text is deleted from the file, not painted over
Signature pad — draw with mouse, trackpad, or touch
Signature — stamped onto the page
Forms — values written into the real AcroForm fields
Compare — line-by-line diff of two versions
Export — page ranges, split, stamps, document properties
On-device AI — ask questions about your document, nothing uploaded
Mobile — bottom toolbar, full-width pages
Everything happens in your browser — your file is opened, edited, and saved on your own machine. The pipeline:
- Open — the PDF loads into browser memory. Nothing is uploaded.
- Edit — the Edit tool rewrites the page's content stream: the original text is deleted from the file and your replacement is written in as real vector text.
- Fill & sign — values go into the real AcroForm fields; signatures are drawn on the page. Flatten at export to lock them in.
- OCR — scanned pages get a text layer from on-device Tesseract, making them searchable, editable, and redactable.
- Redact — you draw boxes over what must disappear. In the editor these are marked for redaction (hatched): a promise, not a removal. Nothing is deleted yet.
- Export — the file is rebuilt from scratch. This is where redaction destroys content: fully covered text is deleted from the content streams (recursively through nested form objects); anything that can't be proven removable (partially covered text, images, exotic fonts) forces the page to be rendered to pixels with the boxes burned in and the original content discarded; form values, annotations, accessibility-tree text, metadata, XMP, attachments, JavaScript, and thumbnails under the boxes are scrubbed. Then the finished file is scanned for every covered string across multiple encodings — if anything redacted is still recoverable, no file is delivered; export fails loudly instead of handing you a file that leaks.
After export the app shows a verification report (regions redacted, strings checked, recoverable: zero). Whiteout, by contrast, is visual-only — it covers content without removing it. Use redaction for sensitive data.
Full detail: How it works — docs
PDF Studio is the zero-setup option that keeps a full editor and never uploads your files. Full breakdown: COMPARISONS.md · web version
What PDF Studio does not do yet:
- Text editing needs a real text layer. Scanned pages go through the on device OCR first.
- Replacement text uses Helvetica metrics, so on exotic embedded fonts the match is near identical, not glyph perfect.
- The on device AI runs small models (0.5B to 1B). It summarizes your document and answers questions about it well. It is not a frontier model.
- There is no real time collaboration and no cloud sync. Autosave lives in the browser you used.
- Signatures are drawn signatures placed on the page, not certified digital signatures.
| 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? | Mostly. The app and OCR engine are bundled and work offline. Only the optional AI assistant downloads model weights (from Hugging Face, on first use). Skip the AI assistant on an offline network; the model source cannot be changed to an internal mirror yet. |
Security assessment — 2026-09-28 — overall grade A−. Each claim was checked against the source code. Full assessment: SECURITY_ASSESSMENT.md · agentic (CLI/MCP) addendum · reporting policy.
Residual risks (stated plainly): autosave is plaintext on your disk, so wipe after use on a shared machine; AI model weights come from HuggingFace over TLS without hash verification. Neither lets data leave your device.
Found something? Please report it privately — see SECURITY.md.
git clone https://github.com/Kayforkind/NavigatorsLab-PDF-Studio
cd NavigatorsLab-PDF-Studio
npm install
npm run dev # http://localhost:5199
npm test # 87 app tests
npm run test:packages # core, CLI, and MCP tests (builds packages first)
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 (87): i18n (language detection, switching, persistence, wipe, catalog completeness) · 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.
PDF Studio ships in English, Spanish, German, and French, and the whole UI is localizable — the app bundles its translations, so switching languages works fully offline. If you speak another language, you can help:
- No code needed: translations are managed in Crowdin (link in the pinned issue) — translate or vote on strings in your browser.
- With code: edit
src/locales/<lang>/translation.json(copy the English keys fromsrc/locales/en/translation.json, keep every{{placeholder}}and<b>/<code>tag intact), then runnpm test -- src/lib/i18n.test.ts— the catalog-completeness tests verify your file key-for-key against English.
New languages are picked up automatically once the JSON file exists and the language is registered in src/i18n.ts (LANGUAGES).
PDF Studio ships two agent native interfaces that reuse the exact same content stream engine as the app. No new parsing code, no network calls, document bytes never leave the machine.
npm install
npm run build:packagesRun the CLI from the repo root with npx pdfstudio …, or make it global with npm link -w packages/cli and then call pdfstudio anywhere. The MCP server lives at packages/mcp/dist/index.js after the build.
Every command and tool is documented on the docs site: CLI reference · MCP reference.
Main CLI commands: pdfstudio info, extract-text, search, edit-text, redact, merge, split, rotate, pages. The MCP server exposes matching pdf_* tools. For least privilege, --read-only registers only the three read tools. Paths are realpath-resolved inside --root, and symlink escapes are rejected.
Conventions: - reads stdin, -o - writes to stdout, reports go to stderr. Exit codes: 0 ok, 1 error, 2 no matches or nothing changed. --json on read commands for scripting.
Claude Code:
claude mcp add pdfstudio -- node /path/to/NavigatorsLab-PDF-Studio/packages/mcp/dist/index.js --root /path/to/your/docsCursor / Cline / any MCP client (mcp.json):
{
"mcpServers": {
"pdfstudio": {
"command": "node",
"args": ["/path/to/NavigatorsLab-PDF-Studio/packages/mcp/dist/index.js", "--root", "/path/to/your/docs"]
}
}
}Privacy guarantee for agents: the CLI and MCP server make zero network calls. Same as the web app: parsing (pdf.js), editing (content stream rewriting), and writing (pdf-lib) all run in process. Redaction deletes the text operators from the file, and the output is rebuilt so orphaned bytes are gone too.
Prompt injection note: PDF content is untrusted input. Extraction and search results are delimited and labeled as data. Agents should treat document text as data, never as instructions. If your agent framework echoes tool output into its context, keep that boundary in mind.
Zero backend, so self-hosting is one command. Images publish to GHCR on every release:
docker run -d -p 8080:80 --name pdf-studio ghcr.io/kayforkind/navigatorslab-pdf-studio:latest
# → http://localhost:8080Or build it yourself:
docker build -t pdf-studio .
docker run -d -p 8080:80 pdf-studioThe container serves the static dist/ build behind nginx — your documents still never leave the machine running it.
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.