Placing a drawn signature on a PDF in your browser

Sign PDF lets you draw a signature, preview a PDF page, choose a position, and download a new copy without uploading the document to the Toolbox Ninja processing API. It is suitable for adding a visual signature mark to routine forms when the recipient accepts that method. A drawn image is not the same technology as a certificate-backed cryptographic digital signature.

How it works

PDF.js reads the selected file in browser memory and renders the current page to a canvas. A second canvas records mouse or touch strokes in the chosen color. When you click the page, the tool stores the position as proportions of the rendered page so it can place the signature into the PDF with pdf-lib. The signed copy is generated locally and downloaded by the browser. Changing pages clears the current placement, and this interface places the drawn mark on one selected page per generated output.

Steps

Open the correct document. Select a PDF and use the page controls to find the signature field. Confirm the filename, page count, and document version before drawing anything.
Draw a clean signature mark. Use the pad with a mouse, stylus, or touch input. Choose an appropriate ink color, clear accidental strokes, and adjust the displayed width before placement.
Place and refine the mark. Click the intended page location, then drag the preview if necessary. Keep the mark within the visible page and avoid covering dates, names, checkboxes, or contractual text.
Download and verify. Generate the signed copy, reopen it from disk, and inspect the signature at several zoom levels. Send it only after confirming the correct page, document revision, and recipient requirements.

Practical use cases

A freelancer can place a visible signature on a straightforward approval form when the client has confirmed that an image signature is acceptable.

A participant can sign a consent or attendance document locally on a shared network where uploading the PDF to a conversion server is undesirable, then remove the local copy after delivery if required.

Limitations

This creates a visible mark, not identity verification, a trusted timestamp, tamper evidence, or a certificate chain. Its legal acceptance depends on jurisdiction, agreement, intent, and the receiving organization’s process. Complex, encrypted, damaged, or unusual PDFs may fail to render or save. The tool does not fill other fields, collect witnesses, lock the document, or preserve existing cryptographic signatures. Browser memory and device performance limit very large files. Always follow the recipient’s specified signing platform when one is required.

Privacy and file retention

The PDF and signature drawing are processed in the browser and are not sent to the Toolbox Ninja tool server. They remain in browser memory until the page is reset, closed, or refreshed, while the downloaded PDF remains wherever your browser saves it. Device backups, browser extensions, managed-device monitoring, and shared download folders are outside the page’s control; use a trusted device and clean up local files according to policy.

Frequently asked questions

Is this a cryptographic digital signature?: No. It embeds a drawn signature image. It does not use a signing certificate or prove that the PDF has not changed afterward.
Can I place signatures on several pages at once?: This interface prepares one placement on the selected page for an output. For multiple controlled signatures, use an approved PDF editor or repeat carefully on successive copies while verifying each result.
Does the PDF leave my browser?: The signing implementation reads and writes the PDF client-side. The page itself does not upload it to the Toolbox Ninja processing endpoint, although normal device and browser security still matters.