How to Add a Stamp to a PDF

Not everything you add to a document is a signature. A company seal on an invoice. An "APPROVED" mark on a purchase order. A "PAID" stamp on a receipt. A registered logo on a certificate. These are stamps — marks of authority or status, placed at a specific spot on a specific page.

The Sign PDF tool handles them alongside signatures, and this guide covers adding one — plus the more useful question of which of the three overlapping tools (stamp, signature, watermark) you actually want.

The steps

1. Open Blackpdf's Sign PDF tool and drop your document in.

2. Click Add Stamp. You create it the same three ways as a signature:

   • Upload — the usual choice. Upload your company seal, logo, or scanned rubber stamp as an image.
   • Type — enter text like APPROVED, PAID, or CONFIDENTIAL.
   • Draw — sketch a mark freehand.

3. Place it on the page. Drag it where it belongs and resize it. Stamps usually sit in a corner, over a signature block, or across a total.

4. Add more if you need them — a stamp on every page, or different stamps in different places.

5. Finish, flatten, and download. Flattening merges the stamp permanently into the page so it can't be dragged off by whoever receives the file.

Stamp, signature, or watermark?

The three overlap, and picking the wrong one is the usual mistake. They differ by what they mean and where they go:

• Signature — "I, personally, agree to this." One or two per document, placed on a signature line. Use Sign PDF.
• Stamp — "this document has a status or an authority." A seal, a logo, an APPROVED/PAID mark. Placed at a specific spot on specific pages. This guide.
• Watermark — "this applies to the whole document." DRAFT, CONFIDENTIAL, a company name — typically large, semi-transparent, tiled or centred, and applied to every page at once.

The practical test: if you want the same mark on every page, diagonally across the content, use a watermark — it's built for that and takes one action. If you want a specific mark at a specific place, use a stamp.

Getting a clean stamp image

If you're uploading a company seal or scanned rubber stamp, the background is what makes or breaks it:

• A PNG with a transparent background is ideal — the stamp sits cleanly on the document with nothing around it.
• A photo or scan on white paper works, but a grey or shadowed background will show as a visible rectangle around your stamp. Run it through Enhance PDF first to force the background to true white.

Common questions

Can I put the same stamp on every page?

You can place one on each page, but if that's the goal, a watermark is the right tool — it applies to the whole document in a single action instead of page by page.

Does a stamp make the document official or legally binding?

No. A stamp is a picture — it carries whatever authority your organisation's process gives it, not any legal force of its own. If you need cryptographic proof of who approved a document and that it hasn't changed since, that's a digital signature; see our digital vs electronic signature guide.

Can someone remove my stamp?

If you don't flatten, yes — it stays a separate object that a PDF editor can select and delete. Flatten before sending, which merges it into the page content. Our flattening guide explains what that does.

My stamp has an ugly white box around it.

Your image has a solid background. Use a PNG with transparency, or enhance the scan so the background is pure white and blends into the page.

Can I stamp a password-protected PDF?

Not directly. Unlock it first, stamp it, then re-protect it if needed.

Wrap-up

1. Open Sign PDF and click Add Stamp.
2. Upload a seal or logo (transparent PNG is best), or Type a mark like APPROVED.
3. Place and size it, then flatten so it can't be removed.

Use a stamp for a specific mark in a specific place, a signature for personal assent, and a watermark when the same mark should cover every page.