Paperweight

Most online PDF editors want your file on their server. For a signed contract, a visa form or a scan of an ID, that is the wrong place for it. And the free ones add a watermark or a page limit once you are done.

Paperweight edits real PDF text, forms and signatures with no server at all.

A static site whose PDF engine runs in your browser.

• Edit existing text. Click a line and retype it. The font the document already embeds is reused when it has the glyphs, otherwise a metric-compatible substitute is used and the app says so.
• Fill forms. Values go in through the form itself, so the filled form prints correctly and other software can still read it.
• Remove and add signatures. Removal takes the signature out of the file rather than painting over it. Adding one works by drawing, typing or uploading a photo.
• Read scans. On-device OCR with a confidence score per line.

Paperweight has no language model, on purpose: sending a document to a model would break the one promise it makes.

• On-device recognition. OCR runs in the browser. A scanned page has no text, only pixels, so the app reads it with a confidence score and calls the result a recognition guess.
• Honest about what is an edit and what is a patch. Replacing text on a scan covers the line and draws over it. The interface says it is a patch, and that the covered pixels stay in the file.
• Cover is not redaction. The app never uses that word for anything that leaves content in the file.

The risky parts were proved first, as spikes inside the real project: text replacement on ten real documents, object removal with a render diff, font fallback, signature removal on a signed sample. A privacy check in CI fails if a single cross-origin request is made while a document is open. Deploys run from CI with wrangler.

• Text edits never reflow. PDF has no paragraph model, so a longer line is condensed, then shrunk, then flagged as overflowing.
• Editing a digitally signed document invalidates the signature. That is the mechanism working as designed, and the app tells you when the document opens.
• Saving over the original needs the File System Access API. Outside Chromium it downloads a copy instead.
• Printing and offline mode are not yet verified by hand in Firefox and Safari. The task list marks them open, because Playwright’s WebKit is not Safari.