GitHub Open Video
pdf.js and pdf-lib · load on first use

Edit any
PDF

Highlight, write, draw, sign and leave notes, then save a real PDF. Your file stays in this browser; nothing is uploaded.

Drop a PDF here It opens right here. Nothing is uploaded.

Your signature

Sign with your mouse, finger or pen

Your signature is kept only in this tab. Click a page to place it, then drag to move or pull the corner to resize.

How it works

Edit: pdf.js (Apache-2.0) draws each page on your screen. Your highlights, text, ink, signatures and notes sit on top until you press Save, then pdf-lib (MIT) writes them into the PDF itself: highlights as see-through rectangles, text in Helvetica, ink as vector lines, signatures as images and notes as standard PDF comments.

Convert: merge, split, rotate and image to PDF copy pages without re-rendering, so text stays sharp and searchable. PDF to images and Compress render pages with pdf.js; Compress rebuilds the file from JPEGs, so text stops being selectable. Zips are made with fflate (MIT).

Ask: pulls the text out of the PDF in your browser and sends up to 12,000 characters of it, with your question, to Llama 3.3 70B on Cloudflare Workers AI. Edit and Convert never send anything anywhere.

Sign: fill a contract template or upload a PDF, place fields for each signer and create an envelope. Your browser encrypts the PDF, the fields and the details with a random AES-GCM 256 key and uploads only ciphertext. The key rides in each signer's link after the #, which browsers never send to a server. Chucksi enforces the signing order, logs each step with time, IP and device, and signs the audit trail with an ECDSA P-256 key. The final PDF gets a Certificate of Completion, and Verify proves a file is unchanged. Unsigned envelopes are deleted after 30 days, completed ones after 90. Chucksi Sign provides templates and signing tools, not legal advice.

Models & limits

Reading and rendering: pdf.js (Apache-2.0), in your browser. Writing: pdf-lib (MIT), in your browser. Zips: fflate (MIT), in your browser. Ask: Llama 3.3 70B (Llama 3.3 Community License) on Workers AI, free within a daily cap. Sign: Web Crypto in your browser, ciphertext in Cloudflare R2 and D1 on the free tier, script fonts from Fontsource (OFL). Cost: $0.