A freelance consultant shares a pricing proposal with a prospective client before a contract is signed. Without a visible watermark, that document could be forwarded to a competitor or used to undercut the proposal. A design agency sends a 20-page brand guidelines PDF for review and approval. Sending it without a DRAFT stamp means the client might treat an unfinished version as the final deliverable. A legal team distributes an internal policy document and needs every page clearly marked CONFIDENTIAL before it leaves the organization.
All three need a watermark added to a PDF, quickly, without uploading a sensitive document to an unknown server. This tool handles text, diagonal stamps, and image watermarks entirely in the browser using PDF-Lib. Choose opacity, position, layer, and page range. A live preview shows exactly how the watermark will look on page one before you apply it to the full document.
How It Works
- Upload your PDF by dragging it onto the upload area or clicking to browse. The document loads with a live preview panel on the right. Navigate pages before setting up the watermark to confirm the content and layout you are working with.
- Choose a watermark type and configure it from three options. Text Watermark lets you enter any text, set font size, color, opacity, position (center, diagonal, corners, top or bottom center), rotation angle, font style (bold/italic/bold italic/normal), and outline style. Diagonal Stamp provides quick preset stamps including DRAFT, CONFIDENTIAL, APPROVED, REJECTED, SAMPLE, COPY, and TOP SECRET with a custom color, opacity, font size, and fill style (filled text, outline only, or with border box). Image Watermark accepts a PNG file (transparent backgrounds recommended), with position controls including Tiled for a repeating grid pattern, plus opacity, scale percentage, and rotation. Set the Apply to option: All Pages, Odd Pages Only, Even Pages Only, First Page Only, or a Custom Range. Choose Layer: Over Content places the watermark visibly on top of existing text and images; Under Content places it beneath for a subtle background effect.
- Preview and apply by clicking Preview to confirm the appearance on page one before committing. Click Add Watermark when ready. PDF-Lib draws vector text paths or embeds the image directly onto each targeted page at your specified coordinates and opacity. Download the watermarked PDF immediately.
Compatibility & Support
Supported Input and Output
- Input: Any standard PDF (text-based, scanned, form-based, multi-page)
- Watermark types: Text (custom text, full style controls), Diagonal Stamp (8 presets plus custom settings), Image (PNG recommended, all positions including Tiled)
- Output: PDF with watermarks embedded as vector paths (text) or image objects per page
- Page targeting: All pages, Odd only, Even only, First page only, Custom range
- Layer options: Over content (foreground), Under content (background)
What to Be Aware Of
Watermarks added through this tool are embedded into the page content layer but are not cryptographically secured. A determined recipient with PDF editing software could remove them. For truly tamper-resistant document protection, combine watermarking with PDF password protection using the Protect PDF tool. For PNG image watermarks, use a transparent background to avoid a solid rectangle appearing around the logo on the page.
File Size Limits
All processing runs in-browser via PDF-Lib with no server upload, so no external size cap applies. Image watermarks from high-resolution PNG files will add proportional size overhead to the output PDF. For large-batch or heavyweight documents, choosing the Text or Diagonal Stamp type rather than Image watermarks keeps the output file size increase minimal.
Who Should Use This Tool?
- Students: A student sharing thesis drafts with a supervisor for feedback can add a diagonal DRAFT stamp to every page, making it clear the document is a working version and should not be cited or redistributed as a final submission.
- Freelancers & Designers: A freelance designer delivering a first-round brand identity PDF for client review can stamp every page with a semi-transparent SAMPLE or DRAFT watermark, preventing the client from using the design before the final payment is received.
- Office Professionals: An HR manager distributing internal salary bands, headcount plans, or legal briefings as PDFs can add a CONFIDENTIAL diagonal stamp to all pages before sending, reinforcing the sensitivity of the content with each person who opens the document.
- Developers: A developer generating report PDFs from an application can use this tool to prototype watermark positioning and opacity for DRAFT or WATERMARK stamps before implementing the same logic in the production PDF generation pipeline.
Key Features
Here's what separates this tool from generic alternatives:
No Server Upload
PDF-Lib processes everything in your browser. Confidential proposals, legal documents, financial reports, and HR materials never transfer to any external server at any point during the watermarking process.
Eight Diagonal Stamp Presets
DRAFT, CONFIDENTIAL, APPROVED, REJECTED, SAMPLE, COPY, TOP SECRET, and WATERMARK are available in one click with full customization of color, size, and fill style. No need to type and format a stamp from scratch for the most common use cases.
Image Watermark with Tiled Option
Upload a company logo as PNG and apply it as a single centered mark or as a repeating tiled pattern across every page. Tiled positioning ensures the watermark covers the full page area and is visible regardless of where someone tries to crop the content.
Foreground or Background Layer
Place the watermark over content for maximum visibility, or under content for a subtle background mark that keeps the main text fully readable. Most basic watermark tools apply only foreground placement with no layer control.
Live Preview Before Applying
The preview panel shows how the watermark looks on page one before you apply it to the full document. Adjust opacity, position, and style until the preview matches your intent, then apply in one click.
Per-Page and Pattern Targeting
Apply watermarks to all pages, odd or even pages only, the first page only, or a custom range. Odd/even targeting is useful for two-sided print layouts where the watermark position needs to mirror between left and right pages.
Why This Tool Beats the Alternatives
- No account, email, or signup required at any point.
- No watermarks added to the output PDF by the tool itself, only the ones you configure.
- No server upload; sensitive documents stay in the browser throughout the entire watermarking process.
- Three watermark types (text, diagonal stamp, image) in one interface; many free tools offer only text or only image watermarks.
- Eight pre-built diagonal stamp presets including CONFIDENTIAL and DRAFT for instant professional stamping without manual formatting.
- Foreground and background layer control, a feature absent from most free watermark tools.
Pro Tips
- For the most visible and repositioning-resistant text watermark, use Diagonal positioning with a rotation of 45 degrees, font size between 60 and 80pt, opacity at 25 to 35%, and the Over Content layer. This combination produces a mark that covers the key reading area of every page and sits directly over the text, making it visible without being illegible from a reading distance.
- When using a company logo as an image watermark, always use a PNG with a transparent background. If a JPG or PNG without transparency is used, the watermark includes the image's background color as a solid block, which covers the document content beneath it. A transparent PNG logo sits cleanly on top of any document color without the background box.
- After watermarking, if you need the marks to be permanently merged into the page content so they cannot be removed by selecting and deleting the watermark layer in an editor, run the output through the Flatten PDF tool. Flattening converts all content layers into a single static page image, making watermark removal effectively impossible with standard tools.
Upload your PDF, choose your watermark type, preview on page one, and download the stamped document in seconds. If you receive a PDF that already has an unwanted watermark and need to remove it, the Remove Watermark from PDF tool handles that in the same browser-based workflow.