Add watermark to PDF online

How to add a watermark to a PDF

1. Choose a PDF file.
2. Enter the watermark text you want, such as DRAFT or CONFIDENTIAL.
3. Set the opacity: lower values are more subtle, higher values are more visible.
4. Click Add watermark.
5. Preview the result to confirm the text is readable but not overwhelming, then download.

The watermark is added as a diagonal text overlay across the center of every page. It is a visible marking, not a security or copy-protection feature.

What this does and how it works

This tool draws your chosen text diagonally across the center of every page in the PDF, at the opacity you choose, using a bold standard font. The text is measured and centered based on its length at the chosen size, so both short text (like "DRAFT") and longer text (like "INTERNAL USE ONLY") are centered correctly rather than overflowing the page. The watermark becomes part of each page's content.

Best practices

• Keep watermark text short. Short phrases like DRAFT, SAMPLE, or CONFIDENTIAL stay legible at a large diagonal size; long sentences become cramped or run off the page edges.
• Use a lower opacity (20-35%) for documents that still need to be read normally, and a higher opacity only when the watermark itself is the point (like a heavily marked sample).
• Preview before downloading to check the watermark doesn't obscure critical content like a signature line or a small table.
• Keep the unwatermarked original file in case you need a clean copy later; this tool always produces a new, separate output file.

Common mistakes to avoid

• Treating a visible watermark as document security. This is a visible marking only; it does not encrypt the file, prevent copying, or restrict editing in any way.
• Setting opacity too high on a document people still need to read closely, which can make body text hard to read underneath a heavy overlay.
• Expecting the watermark to be removable later by this site's tools. Once applied and saved, the watermark is part of the page content; removing it would require different, more complex editing than this site offers.

Real-world use cases

• Marking a document as DRAFT before it's finalized and circulated.
• Marking pages as CONFIDENTIAL before sharing outside your organization.
• Adding SAMPLE across preview pages shared before a purchase or full release.
• Marking a document with a case or reference number for internal tracking.
• Distinguishing multiple versions of the same document circulating for review, such as watermarking "V2" or "REVISED" so recipients don't confuse it with an earlier copy.

Supported formats

Input: a single standard, non-encrypted PDF file. Output: the same PDF with a diagonal text watermark added to every page. Image-based watermarks (like a logo) are not currently supported; only text watermarks are available. If you need a logo or graphic on every page, that would need to be added through different PDF editing software.

Worked example: comparing opacity levels

The same "CONFIDENTIAL" watermark looks very different depending on the opacity setting chosen:

Limitations

This tool cannot open password-protected or encrypted PDFs. It applies the same text, opacity, and diagonal placement to every page; there is no per-page customization or image/logo watermark option in this version. It is a visible marking only and provides no copy protection, encryption, or access control — and, as noted on the PDF Tools hub, this site does not offer PDF encryption or password protection for that reason.

Privacy

Your PDF is read and watermarked locally in your browser using the pdf-lib JavaScript library loaded from this site. Files are not uploaded to a server. See the privacy policy for full detail.

Troubleshooting

• If the watermark text runs off the page, shorten the text; very long phrases can extend past page edges at a large diagonal size.
• If the watermark is too faint or too strong, adjust the opacity and try again.
• If you need to remove a watermark that was added by another tool, this site does not offer watermark removal, since there's no reliable generic way to detect and undo an arbitrary existing watermark.

Choosing wording that signals intent clearly

The wording you choose affects how a reader treats the document. "DRAFT" signals the content may still change and shouldn't be treated as final. "CONFIDENTIAL" signals restricted distribution without specifying a formal handling policy. "SAMPLE" signals the document is a preview, often paired with limited or altered content. "INTERNAL USE ONLY" signals a distribution boundary within an organization. Pick wording that matches what you actually mean; a watermark that says CONFIDENTIAL on a document that's actually just an early draft can cause confusion about why it's being restricted, when DRAFT would communicate the real concern more precisely.

Conclusion

Use this tool to mark a PDF's pages with DRAFT, CONFIDENTIAL, SAMPLE, or similar text for visibility, not for security. For an actual size reduction after marking, run the result through compress PDF; to combine a watermarked file with others, use merge PDF.