How to Add a Watermark to a PDF (Free)

Go to PixelTools' [Watermark PDF tool](/watermark-pdf), drop in your file, and choose a text or image (logo) watermark. Type your text or upload a logo, then adjust opacity, rotation, and position before downloading. Everything runs in your browser using pdf-lib — the PDF is never uploaded to a server, and nothing is installed. The watermark is applied to every page (or a page-number subset) in one pass, so a 50-page contract takes the same one step as a single-page document, and the file downloads ready to send as soon as processing finishes.

A text watermark ("DRAFT," "CONFIDENTIAL," a company name) is the fastest option and works for most document-marking needs — you control the font size as a percentage of the page width, so it scales correctly whether the PDF is A4 or a wide spreadsheet export. A logo or image watermark is better when brand consistency matters, like stamping every page of a proposal with a company mark. PixelTools' tool supports both from the same interface, and you don't need to flatten or re-export anything — just pick the type and the rest of the controls (opacity, rotation, position) work the same way for either.

The tool places the watermark on a 9-point anchor grid (top/center/bottom crossed with left/center/right), plus a rotation control from -180° to 180° for the classic diagonal "CONFIDENTIAL" look. For documents likely to be printed and re-photocopied, tile mode repeats the watermark across the full page at a spacing you set as a percentage of the page's shorter dimension — denser tiling makes the mark harder to crop out of a single copy, at the cost of being more visually intrusive. A single centered or diagonal watermark is usually enough for routine drafts; tiling is worth the extra visual weight mainly for documents where someone might try to crop the mark out.

Opacity is the setting most people get wrong in either direction. Too low (under ~15%) and the watermark barely reads in print or on a low-brightness screen. Too high (above ~50%) and it starts to interfere with reading the underlying text, especially over dense paragraphs. A range of 20-35% opacity is a reasonable starting point for most "DRAFT" or "CONFIDENTIAL" marks — visible enough to register at a glance, faint enough that the document underneath stays fully legible. If the PDF is mostly white space (a form, a certificate), you can push opacity higher without hurting readability.

Watermarking makes sense any time a document needs to signal its status or origin without changing its content: marking a contract draft before it's finalized, stamping "CONFIDENTIAL" on internal financials before sharing outside the company, adding a firm's logo to every page of a client deliverable, or marking sample/preview pages of a paid PDF product before the full version is purchased. It's not a security measure — a watermark can be cropped or edited out by someone determined enough — so don't rely on it to protect genuinely sensitive content; for that, PDF encryption or access controls are the right tool, not a watermark.