High-fidelity rendering
PDFium — the same engine powering Chrome's PDF viewer — runs as WASM in the browser and native on desktop. Identical pixel output on both surfaces (render-parity CI gate: diff <0.22%).
Casual PDF · v1 in progress
One PDF engine. Every surface.
A high-fidelity PDF viewer and editor — one PDFium engine across web and desktop, identical rendering everywhere. Annotate, fill forms, edit text in place, e-sign, redact, and organise pages. No SaaS. Apache-2.0.
what it does A full Tier-1 PDF editor,
/features A full Tier-1 PDF editor,
built on one engine.
Annotation suite
Highlight, ink, free-text, note, rectangle, ellipse, arrow. Undo/redo. Multi-select with rubber-band marquee. Annotations bake into the PDF on download via the EmbedPDF export plugin.
In-place text editing
Edit existing PDF text directly — click a run, type, commit. PDFium's
text-object API (FPDFText_SetText) edits content in-place without
rasterising. Fail-closed for subsetted fonts: falls back to standard Helvetica/Times/Courier and shows a banner.
E-signing + PKCS#7
Two signing modes: a visible signature stamp (draw or type, placed as
an annotation) and a certified PKCS#7 cryptographic signature via
@signpdf/signpdf — incremental update preserves original bytes.
Browser-minted self-signed or your own .p12/.pfx.
True byte-level redaction
Drag to mark regions. Apply rasterises each page at 2×, paints opaque black boxes, then rebuilds with pdf-lib — preserving MediaBox origin, CropBox, and rotation. Content removed by construction: not in the output bytes. Immune to de-redaction attacks (arXiv:2206.02285).
Page operations + furniture
Drag to reorder or delete pages (Organize Pages). Watermark, header/footer
(with {page} / {pages} / {date}),
and Bates numbering — all stamped via pdf-lib as incremental updates.
tech stack
/architecture One engine, three surfaces.
Engine
- PDFium-WASM via EmbedPDF (MIT) — web + desktop webview
- pdfium-render (Apache/MIT) — native Rust, CI render-parity
- One Rust crate (
casual-pdf-core) → wasm32 + native
Write side
- pdf-lib — redaction, page furniture, image stamps
- @signpdf/signpdf + node-forge — PKCS#7 (BSD-3)
- Incremental update: original bytes preserved, signatures valid
UI + collab
- React 18 + Vite + TypeScript + @schnsrw/design-system
- EmbedPDF plugins — annotation, history, export, form, signature
- Yjs overlay (deferred) — collab deprioritised; solo w/ autosave today
honest scope
What Tier 1 means — and what it doesn't.
Tier 1 — ships in v1
- Annotate (highlight, ink, shapes, notes)
- Fill interactive AcroForm fields
- In-place text editing (non-subsetted fonts; fallback for subset)
- E-sign: visible stamp + certified PKCS#7
- True byte-level redaction (rasterise + flatten)
- Organise pages (reorder, delete)
- Watermark · header/footer · Bates numbering
- Search, selection, thumbnails, outline, fullscreen
- Crash recovery + autosave (IndexedDB)
Tier 2 — later
- Full paragraph reflow when edited text changes width
- New page creation, complex layout editing
- Real-time co-editing via services/collab
- Public share links + granular viewer/commenter/signer rights
PDF is not a reflowable format — full reflow is Adobe's moat. Tier 1 in-place editing is already more than most non-Adobe tools ship.
Try it
PDF editing that doesn't
PDF editing that doesn't
phone home.
Open a PDF, edit it, sign it, redact it — everything runs in your browser. No account, no upload, no SaaS. Apache-2.0.