Add Watermark to PDF

The PDF Watermark tool adds text watermarks across every page (or selected pages) of a PDF document. Protect copyright on published documents, mark drafts before review circulation, brand outgoing PDFs with your company name, or add \\\"CONFIDENTIAL\\\" overlay to sensitive documents. Configure appearance with font family, size, color, opacity, rotation angle, and position.

Upload your PDF, enter watermark text, customize appearance, choose placement (center, corner, diagonal, tiled, or custom position), and download. Options to apply to all pages or specific ranges. Watermarks are added as native PDF text (not rasterized), keeping file size small and preserving text searchability. All processing runs in your browser so original documents stay private.

PDF watermarking adds text or images as an overlay on existing pages. Using pdf-lib:

1. Parse PDF
2. For each page in target range:
- Get page dimensions and existing content
- Draw watermark text on top with specified font, size, color, opacity
- Apply transforms (rotation, position)
3. Save modified PDF

Text is added as actual PDF text (not rasterized), so:
- File size stays small
- Watermark text is selectable and searchable
- Quality is perfect at any zoom

Font embedding: to use non-standard fonts, the font must be embedded. Standard PDF fonts (Helvetica, Times, Courier, and their variants) are built into readers; custom fonts need embedding. This adds to file size.

Opacity: set fill color with alpha for transparent effect. Common watermark opacity is 20-50% for visibility without overwhelming content.

Position options:
- Center: prominent, hard to ignore
- Corner: subtle, copyright-style placement
- Header/footer: thin watermark at top or bottom of each page
- Diagonal: rotated 30-45 degrees for dramatic \\\"DRAFT\\\" look
- Tiled: repeated across whole page, hardest to remove

Rotation: applying angle like -45 for diagonal watermarks. Text is drawn with transform matrix applied.

Z-order: watermark can be below original content (background, hard to remove) or above (foreground, obvious). Above is more visible; below can be more professional.

Per-page options: different watermarks on different pages, or skip specific pages like cover pages.

Image watermarks: logos or signature images embedded as PDF images overlaid on pages. This tool focuses on text; for image watermarks, use a more advanced tool.

Performance: watermarking is relatively fast — adding text to existing pages. 100-page PDFs watermark in seconds.

Security note: text watermarks can be removed by image-level PDF editors (but removing requires re-saving PDF). They deter casual sharing, don\u2019t prevent determined extraction. For real protection, use encryption + DRM, not just watermarks.

Compared to Adobe Acrobat Pro\u2019s watermark feature, this tool is free and browser-based. Acrobat offers image watermarks and more formatting; this tool covers text watermarks completely.

Compared to flattening PDF to images and watermarking, this tool preserves text searchability and quality. Rasterizing loses searchable text and quality.

Compared to online PDF watermark services, this tool runs entirely in your browser without upload. Keep documents private.