Frequently asked questions

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 stamped over content. PDF Studio rewrites the content stream: original text operators are deleted from the file, and replacements are written in as real vector text.

Does my document leave my device?

Never. There is no upload endpoint and no server. The only network use is user-triggered: downloading AI model weights from HuggingFace (once, cached), which contain no document data. See Security.

Does it work offline?

Yes. Install the PWA for a fullscreen offline-capable app, or self-host with Docker. AI and OCR models work offline after their one-time download.

What's the difference between redaction and whiteout?

Redaction (B) permanently removes covered content from the file — text operators are deleted, and pages are rasterized where text can't be proven removable. Whiteout (W) only covers content with the page-sampled background color; the underlying text is still in the file and is not secure. Use redaction for sensitive data. See Redaction.

Honest limits?

• Text editing needs a text layer. Flat scans go through the OCR tool first.
• 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 and answering questions about your document, not a frontier model.

Can I automate PDF Studio?

Yes — v1.1.0 added two local, agent-native interfaces reusing the same content-stream engine as the app:

• CLI — pdfstudio with 9 commands: info, extract-text, search, edit-text, redact, merge, split, rotate, pages. Stdin/stdout pipes, --json output, exit codes 0/1/2.
• MCP server — 10 tools (pdf_info, pdf_extract_text, pdf_search_text, pdf_edit_text, pdf_redact_text, pdf_redact_rect, pdf_merge, pdf_split, pdf_rotate, pdf_pages) over stdio, with path containment and prompt-injection hardening.

Both make zero network calls.

How do I report a security issue?

Do not open a public GitHub issue. Email Kazym at kazim.r.merchant@gmail.com with subject [SECURITY] PDF Studio — <short description>. See the vulnerability policy.

How do I contribute?

The repo labels newcomer-friendly work as good first issue. See CONTRIBUTING.md for setup (npm install, npm run dev, npm test, npm run build).

Where is my autosaved session stored?

In your browser's localStorage, on your device only. A one-click "forget" control wipes it completely — use it on shared machines.