PDF Sign, Watermark & Number
View your document and place a signature, text, or watermark exactly where you want. Nothing is uploaded.
Drop a PDF here, or click to choose.
Processed entirely in your browser
How to sign, watermark or number a PDF
- Add your PDF and pick a mode. Choose Signature, Watermark or Numbers.
- Set the details. For a signature, choose a PNG or JPG image and the target page; for a watermark, enter the text and opacity.
- Apply and download. The new PDF is created locally and saved to your downloads.
What happens to your file
The signature image, watermark text or page numbers are embedded directly into the PDF using pdf-lib, running entirely in your browser tab. The document is never uploaded to OpenToolkit.
Because everything runs on-device, there's no server-side size limit — a large document is bound only by your browser's available memory.
What this tool supports
Common reasons to use this tool
- Drop a scanned signature onto a single-page agreement or form.
- Mark drafts "CONFIDENTIAL" or "DRAFT" before circulating them.
- Add page numbers to a report assembled from several sources.
- Brand an internal document with a light watermark before sharing it.
Frequently asked questions
Are my files uploaded anywhere?
No. The signature, watermark or numbering is applied locally in your browser tab; the document is never sent to OpenToolkit.
Is the signature a legally binding digital signature?
No — it places an image of a signature onto the page. It's meant for casual sign-off, not a cryptographic digital signature with identity verification.
Can I place the signature anywhere on the page?
The current tool places it near the bottom-right of the page you choose; it doesn't yet support free positioning.
Can I watermark or number only some pages?
Watermarks and page numbers currently apply to every page in the document.
Can I annotate a password-protected PDF?
Not directly. Unlock it in a PDF application first and use the unprotected copy.
I need to black out content instead of adding a mark — what should I use?
Try PDF Redaction.
Last reviewed: August 2026