Sign a PDF

Draw your signature, drop in a PDF, and place the mark on any page with millimetre coordinates, embedded as a transparent PNG.

Your drawing and your PDF are combined locally with pdf-lib. Neither ever leaves your device.

1 · Draw your signature

Use a mouse, finger or stylus. Undo removes the last stroke.

2 · Choose the PDF to sign

Drop a PDF here or click to browse

3 · Place the signature

Positions are millimetres measured from the bottom-left corner of the page — the same origin PDF uses. There is no rendered page preview: set the numbers, download, and nudge if needed.

How It Works

Your signature is captured on a plain HTML canvas and exported as a transparent PNG; the open-source pdf-lib library then embeds that image into the PDF. Every step happens inside your browser tab — no upload and no page rendering.

A Transparent PNG of Your Drawing
The canvas keeps an alpha channel, so only the ink you drew is exported — the white you see is the page showing through, not part of the image. pdf-lib's image embedding preserves that transparency, which is why the stamp does not cover the text underneath it.
Millimetres from the Bottom-Left
PDF's page coordinate system has its origin at the bottom-left corner with Y growing upward — the same convention as the X and Y fields here, just measured in millimetres instead of points (1 mm = 72/25.4 pt, converted for you). The width control sets the signature's width; its height follows the pad's aspect ratio.
A Stamp, Not a Seal
What gets written is an ordinary image object in the page's content stream: visible to everyone, editable by anyone with a PDF editor, and it does not lock the file. Real tamper evidence requires a cryptographic digital signature with a certificate, which is a different technology this tool deliberately does not fake.

Frequently Asked Questions

Is an electronic signature made like this legally binding?

Broadly, many legal systems (the US ESIGN Act, the EU's eIDAS regulation and equivalents elsewhere) accept a simple electronic signature on most agreements — a drawing you make over your own name on a document expresses intent. What a plain image stamp cannot show is signer authentication and tamper evidence, which is often what disputes turn on. For high-stakes agreements use a signing platform with certificates and an audit trail. Nothing here is legal advice.

Does signing lock the PDF afterwards?

No. This tool pastes your signature as an image onto the page; the file stays fully editable and unencrypted. A true digital signature is different: it applies a cryptographic seal with a certificate so any later edit invalidates it. That requires keys issued by a certificate authority and is out of scope for an in-browser stamp.

How is this different from scanning a wet-ink signature?

Both end up as an image painted onto a PDF — visually there is little difference. The difference is provenance: with a wet-ink scan the paper original existed and a chain of custody can start from it, while a signature applied here has no independent record of when or by whom. If the receiving party demands the wet-ink original, an image in a PDF will not substitute for it.

How do I position it precisely without a page preview?

Use the millimetre model: X and Y are distances from the bottom-left corner of the page, measured the same way a ruler on paper would be. On A4 (210 × 297 mm) a typical signature line sits around X 20–130 and Y 30–60. Apply, open the download, and nudge the numbers — one iteration is usually enough.

Is anything uploaded to a server?

No. Your drawing stays in memory as a transparent PNG and the PDF is parsed, stamped and re-saved with pdf-lib in your browser. There is no upload step, no account, and no network request containing either file.