Add a watermark to a PDF

How it works

1. Drop the PDF to watermark (max 10 MB on Free, 200 MB on Premium).
2. Type the watermark text (up to 50 characters): CONFIDENTIAL, DRAFT, a company name, a date.
3. Click Add watermark. The text is stamped diagonally across every page and you download the result as a new PDF.

A diagonal watermark on every page

The text is drawn at a 45° angle, centered on the page, in semi-transparent grey (30% opacity, 48 pt). The diagonal placement keeps it readable across the whole sheet without hiding the underlying content, and the transparency lets the document stay legible underneath. The same watermark is applied to every page of the document, up to 2,000 pages.

The stamp is non-destructive for your text: the original content is untouched, the watermark is simply drawn on top. The watermark itself uses the standard Helvetica font, so the result opens everywhere — Adobe Reader, macOS Preview, modern browsers (Chrome/Edge/Firefox/Safari) and mobile PDF readers.

Which text works

The watermark is limited to 50 characters, which is plenty for a stamp like CONFIDENTIAL — DO NOT DISTRIBUTE or DRAFT 2026. Standard Latin letters, digits and common punctuation are supported.

Characters outside that range — emoji and non-Latin alphabets (Arabic, Chinese, Cyrillic…) — are not supported by the watermark font and are dropped. If nothing printable remains after filtering, the file is rejected so you can adjust the text. The style (color, opacity, angle, size, position) is fixed in this version; per-page or image watermarks are not available yet.

Privacy and security

The entire operation runs on our servers in France (OVH Gravelines). No US third party is involved in the process — no CDN, no storage, no tracker. Your PDFs are never indexed, analyzed or inspected. The watermark is applied in a single pass, PDF to PDF, with no conv2pdf branding added and no sign-up required.

The source PDF and the watermarked PDF are deleted after one hour. If you create a share link, a copy of the PDF is kept for the period you chose (up to 7 days on Free and 30 days on Premium). You can delete the share (and therefore the PDF) at any time. conv2pdf is GDPR-compliant, and a DPA is available on request for professional use.

Frequently asked questions

Can the watermark be removed later?

Not via conv2pdf. The text is baked into the page rendering, like any other drawn content, so there is no toggle to switch it off. Keep the original PDF if you may need an unmarked copy.

Can I add an image or logo watermark?

Not yet. This version stamps text only. An image or logo watermark is on the roadmap.

Can I change the color, size or position?

Not in this version. The style is fixed: grey, 45° diagonal, centered, 30% opacity, on every page. This covers the most common need — a CONFIDENTIAL or DRAFT stamp — without extra settings.

Does the watermark damage the original text?

No. The underlying content is left as is; the watermark is drawn over it. Text in the PDF stays selectable and searchable.