Watermark PDF FREE | Add Text Watermarks to PDF Online

Add a custom text watermark across every page of your PDF. Set the text, size, opacity, and rotation angle. The watermark is permanently embedded into the PDF and downloads instantly. Free, private, nothing is uploaded.

Private - No Upload

All Pages

Fully Customisable

Free Forever

PDF Watermark Tool

Drop your PDF here

PDF files only

Frequently Asked Questions

Yes. Everything runs locally in your browser using pdf-lib. Your file is never uploaded to any server. It stays entirely on your device throughout the process.

When tiling is enabled, the watermark is repeated in a grid pattern across the entire page, making it much harder to remove or crop out. When disabled, a single centred watermark is placed in the middle of each page.

Yes. The angle slider goes from 0 degrees (horizontal) to 90 degrees (vertical). The default is 45 degrees which places the watermark diagonally across the page, the most common professional watermark style.

No. The watermark text is embedded as a new vector text layer in the document. The original content, images, and text quality are not affected.

About One Doc Studio

One Doc provides Forever Free browser-based tools. Nothing is uploaded. Your files never leave your device.

Free PDF Watermark Tool Online - Add Text Watermarks to Any PDF Instantly

Adding a watermark to a PDF is one of the most effective ways to protect intellectual property, mark draft documents, identify confidential files, and deter unauthorised copying. The PDF Watermark tool on OneDocPDF embeds your custom text watermark permanently into every page of the PDF using pdf-lib, the open-source browser PDF library. The watermark is rendered as a real text layer in the PDF structure, not just a visual overlay, so it appears correctly in every PDF viewer. Choose your text, size, opacity, colour, and rotation angle. Enable tile mode to repeat the watermark across the full page area for maximum protection, or disable it for a single centred watermark.

The default 45-degree diagonal angle is the professional standard for document watermarks because it is impossible to crop out from any corner and overlaps with all areas of page content. Legal firms, financial institutions, and government agencies all use this angle for confidential document distribution. The opacity control lets you balance visibility against readability of the underlying content. A setting of 25-35% is the professional sweet spot, making the watermark clearly visible while keeping the document content fully legible.

For a complete document protection workflow, combine watermarking with our other tools: use our Sign PDF tool to add your signature before or after watermarking, use our Redact PDF tool to remove any sensitive text before distribution, and use our PDF Compressor to reduce the file size of the watermarked output for emailing. Browse all free PDF tools on OneDocPDF.