Add a stamp to a PDF — when DRAFT, CONFIDENTIAL, or APPROVED need to be on every page
Business stamps — DRAFT, CONFIDENTIAL, APPROVED, REJECTED, PAID, VOID — predate computers and are still in heavy use because they communicate document status at a glance. The digital version of rubber-stamping a PDF takes about ten seconds; getting it to look intentional rather than amateur takes knowing about three settings most users do not think about. Here is what the stamp tool does, the twelve preset stamps with the use cases each fits, and the differences between stamping (a visual layer) and redaction (content removal).
How stamping works
The stamp tool draws colored text onto each page's content stream — typically with a colored border and rotated for the classic angled rubber-stamp look. The drawing happens via pdf-lib at vector quality: the stamp text and border are crisp at any zoom level. The original page content is untouched; the stamp sits on top.
Because the stamp is part of the page content rather than an annotation, recipients cannot delete it through the normal annotation-removal flow in Acrobat. A determined recipient with PDF editor software can still remove it (the original page content is intact underneath the stamp), but the casual recipient sees the stamp as part of the document. For irreversible stamping where the underlying content really needs to go, use Redact instead.
Twelve preset stamps and their use cases
The tool ships twelve presets covering the most common workflows:
- DRAFT. The most common stamp. Use on circulated working copies that are not yet final, to signal that changes are still expected.
- CONFIDENTIAL. Reminder that the document should not be redistributed outside the intended audience. Common on internal reports, partner agreements, board materials.
- APPROVED / REJECTED. Review-workflow signals. Use after a sign-off step to mark a document's status.
- PAID / RECEIVED. Invoice and shipping workflow signals. PAID indicates payment processed; RECEIVED indicates physical or digital receipt of goods.
- REVIEWED. Sign-off that a document has been read and acknowledged. Common in compliance workflows.
- COPY / ORIGINAL. Differentiator stamps for cases where you need to mark which physical (or digital) version is the original of record.
- VOID. Cancellation marker. Use on documents that have been replaced or invalidated — keeping them in the record for audit purposes but signaling they should not be acted on.
- FINAL / URGENT. Workflow signals — FINAL marks a document as locked, URGENT signals immediate attention required.
- Custom (up to 30 chars). Type your own. For workflow-specific signals ("CLIENT REVIEW", "BOARD PACK", "FOR DISTRIBUTION"). The 30-char cap keeps the stamp readable at preset sizes.
Three settings that distinguish good stamps from amateur ones
The defaults work most of the time. Adjusting one or two of these settings for context lifts the result:
- Rotation angle. 0° (horizontal) reads as official-document style. -30° to -45° (left-tilted) reads as classic rubber-stamp. +30° to +45° (right-tilted) is unusual; default left-tilt of -15° is the most universally-recognized rubber-stamp angle.
- Opacity. 100% is dense and dominant. 60-80% reads as a stamp that does not obscure the underlying content. For a CONFIDENTIAL stamp on a readable document, 70% is the canonical pick.
- Position vs page content. A stamp dead-center on a page with text in the center collides with the text. Pick a corner position (top-right is most common for DRAFT, top-center for CONFIDENTIAL, diagonal-center for VOID) based on what's already on the page.
Stamp vs Redact — when to use each
These two operations look similar visually but solve different problems:
- Stamp — visual annotation, content intact. Use when the underlying content should still be readable. A CONFIDENTIAL stamp does not hide the document's content; it signals how to treat it.
- Redact — content removed, visual block. Use when the underlying content needs to actually go away. Redact bytes-out the text; the recipient cannot recover it by copy-paste or by removing an overlay.
When to also flatten after stamping
Stamping draws the text into the page content stream. That alone is harder to remove than an annotation. But four cases benefit from also flattening:
- Documents going to recipients with PDF editors. If the recipient has Acrobat Pro or similar, they can still remove the stamp via the editor's content-edit mode. Flattening makes that harder (though not impossible).
- Pre-signing. Stamp first (DRAFT, etc.), then flatten to lock it in, then sign cryptographically. The signature anchors the stamped state.
- Archival. Stamped + flattened PDFs behave more consistently across years of viewer-software updates than annotation-style stamps.
- Re-distribution-risk documents. If the document might get re-shared further than originally intended, flatten lifts the friction of stamp-removal.
Limits and compatibility
On the free web tool, stamping handles PDFs up to 50 MB. Encrypted PDFs need to be unlocked first. Processing runs in your browser via pdf-lib; nothing is uploaded. Output is byte-compatible with every PDF reader.
Common pairings: Stamp → Flatten for irreversible stamping. Stamp → Sign for stamped-and-signed deliverables. Stamp + Add Logo for branded stamped documents (logo in one corner, stamp in another).