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PDF Sign

Draw, type, or upload a signature — then click to place it on any page of your PDF.

Next steps

Organize pages

Drag pages to reorder, rotate individual pages, and delete pages — then export.

Merge PDFs

Merge multiple PDFs into a single file — drag, drop, done.

Compress PDF

Compress PDFs to a fraction of their size — perfect for email.

Protect PDF

Lock sensitive PDFs with a password or remove existing protection.

View all tools →
Runs entirely in your browser. No uploads. Your files stay private.

How to Sign a PDF in the Browser — Drawing, Typing, or Uploading

PDF Sign places a visible signature image into a PDF using two libraries: pdfjs-dist (Mozilla's PDF.js) renders each page onto a canvas so you have an accurate preview to position the signature on, and pdf-lib embeds the resulting signature as a PNG image into the page's content stream when you export. Both libraries run entirely in your browser, so the document never leaves your device.
Three input methods are supported. Draw uses an HTML canvas with pointer event tracking — pen input on iPad and Surface devices is captured at full pressure resolution, and the result is exported as a transparent PNG. Type renders your name in an italic display font onto an offscreen canvas so it looks closer to handwritten signature than a system font. Upload accepts PNG or JPG images of a scanned physical signature; PNGs with a transparent background look best because there is no white rectangle around the strokes.
Click on the page preview to drop a signature. Each placement stores normalized coordinates (relative to the page's media box) so positions remain accurate at any zoom level. Drag a placed signature to reposition, and use the size slider to scale. Multiple placements per page are supported, including initials on every page in a long contract.
On export, pdf-lib embeds the signature PNG using the embedPng method, then draws it on each placed page at the stored coordinates. The output is a standards-compliant PDF that opens identically in Adobe Acrobat, browser PDF viewers, macOS Preview, and mobile readers.
An important distinction: this is a visible electronic signature, not a cryptographic digital signature. Electronic signatures are legally binding in most jurisdictions under laws like the US ESIGN Act and the EU eIDAS regulation when they show clear intent to sign. Cryptographic digital signatures (PKCS #7 / CAdES, the kind that show a green checkmark in Acrobat) require certificates, timestamping authorities, and PDF/A-compliant signing — a workflow that browsers cannot complete without server-side certificate handling.
Encrypted PDFs cannot be parsed by pdf-lib until they are unlocked — use the PDF Password tool first. PDFs with existing digital signatures will see those signatures invalidated by adding a new image; this is part of the PDF signing standard.
Practical limits: PDFs up to ~200 pages and ~100 MB are comfortable. Very long documents slow down because pdfjs-dist renders every page you scroll through. For initialing every page of a 300-page document, splitting into halves with PDF Splitter and signing each separately is faster.

Common Use Cases

01

Sign contracts without printing

Add a drawn or typed signature to a PDF and email it back without ever touching a printer or scanner.

02

Initial every page of a contract

Navigate page-by-page and stamp initials on each, with a placements summary showing how many signatures are on every page.

03

Sign on tablet or phone

Pen input on iPad, Surface, and Android stylus devices captures pressure-aware strokes through pointer events for a natural-looking signature.

04

Embed a scanned ink signature

Upload a transparent PNG of your real signature and place it where you'd normally sign on paper, sized to fit the signature line.

Frequently Asked Questions

Yes for most everyday use. Electronic signatures are recognized as binding under laws like the US ESIGN Act and EU eIDAS when they clearly show intent to sign. For high-value or regulated transactions (real estate closings, notarized documents) a platform with audit trails and identity verification is advisable.
This tool produces a visible electronic signature — an image embedded into the PDF. A digital signature uses PKCS #7 cryptography, a personal certificate, and a timestamp authority to prove identity and integrity. Browsers cannot create those without server-side certificate handling.
No. PDF.js renders pages and pdf-lib embeds the signature, both running inside your browser. The document stays in tab memory and is never transmitted.
Not directly — pdf-lib refuses to parse encrypted streams. Remove the password using the PDF Password tool first, sign, then re-encrypt if needed.
PNG and JPG. For best results use a PNG with a transparent background so the signature appears cleanly on the document without a white rectangle. Aim for at least 600×200 pixels at 300 DPI for sharp edges when zoomed.
Yes. Navigate between pages using the arrows and click to place. The placements panel summarizes how many signatures are on each page before export, and any placement can be deleted or repositioned individually.
Drawn and uploaded signatures are stored as PNGs at the resolution they were captured. For 300 DPI print quality, draw on a high-DPI device or upload a scanned signature at 600×200 pixels or larger. Typed signatures are rendered to canvas at high resolution and stay crisp.
Yes. Any modification to a digitally signed PDF — including adding a visible signature image — invalidates the existing cryptographic signatures. This is part of the PDF signing standard.
Not in this tool. Browser-based certificate signing is impractical because it would require uploading the certificate or installing native code. Desktop Acrobat or qpdf with a signing plugin remain the standard for cryptographic signatures.
There is no hard cap. PDFs up to about 100 MB and 200 pages are comfortable on a modern laptop. Very long documents slow down because every page must be rendered for thumbnail navigation.

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