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Add Watermark to PDF Free - Interactive PDF Stamper
Add watermarks to PDF documents online for free. Standard PDF stamping websites require you to upload your files to remote cloud servers, which raises privacy concerns for scanned personal records, IDs, and financial statements. Jetpap processes your files 100% securely and privately sandbox, keeping your documents secure and private.
Introduction & Overview
Watermarking is a reliable way to protect intellectual property, prevent unauthorized document sharing, and indicate document status. Whether you are marking corporate documents as "DRAFT", stamping legal contracts as "CONFIDENTIAL", or adding your logo to photography catalogs, clear watermarking helps secure your work.
Our **Free Online PDF Watermark Tool** lets you apply both custom text and image stamps to your files. Our interactive drag-and-drop live preview ensures that your watermarks are positioned exactly where you want them.
Core Features & Capabilities
Our local stamping engine provides formatting and placement features:
- Interactive Drag & Drop: Select "Custom" placement mode and drag your watermark to position it on the document preview.
- Text Watermarks: Add custom text with control over fonts (Helvetica, Times, Courier), colors, rotation (0-360°), and opacity (10-100%).
- Image & Logo Watermarks: Upload custom PNG or JPG logos and adjust opacity levels to blend them with the document background.
- Mosaic (Tile) Mode: Repeat the watermark in a grid pattern across the entire page for maximum anti-theft protection.
- Placement Presets: Place watermarks in the center, corners, or set custom coordinate positions.
- Page Range Selection: Apply watermarks to all pages, first page only, last page only, odd pages, or even pages.
How to Use: Step-by-Step Guide
Stamp your documents in five steps:
- Upload File: Select a PDF file from your device, or drag and drop it into the upload box.
- Choose Watermark Type: Select the **Text** or **Image** tab in the sidebar control panel.
- Configure Placement and Format: Set your positioning mode (Center, Corner, Mosaic, or Custom), rotation angle, opacity, and scale size.
- Adjust Position: If using "Custom" mode, click and drag the watermark element on the preview canvas to position it.
- Download: Click **Download PDF** to generate the stamped document and save it securely.
The Technology and Logic Behind It
Jetpap's watermark tool processes files entirely on the client side. The app uses **PDF.js** to parse your document and render page previews onto HTML5 canvas elements.
When you click download, **pdf-lib** modifies the document's binary data structure. The engine embeds the selected fonts or decodes uploaded images, computes the target coordinates (including rotation and scale transformations), and overlays the watermark elements onto the specified pages. Since all processing runs securely, your sensitive document files never leave your device.
Key Benefits of Our Tool
- 100% Secure & Private: secure processing prevents your documents from being uploaded to remote servers.
- Interactive Drag & Drop: Position watermarks on the page visually.
- No Caps or Limits: Stamp documents of any size for free, with no watermarks or registration walls.
- Offline Functionality: Once loaded, the tool can run completely offline.
Frequently Asked Questions
Are my uploaded PDF files secure?
Yes, absolutely. Your PDF documents never leave your secure environment. The entire watermarking process runs secure privately on your device using HTML5 and our processing engine, ensuring 100% security.
Can I watermark only specific pages in a PDF?
Yes. You can specify a custom page range (such as "First Page Only", "Odd Pages", "Even Pages", or individual numbers like "1, 3, 5") to control exactly where the watermark appears.
What is the difference between Center, Custom, and Mosaic modes?
Center places a single stamp in the middle of each page. Custom lets you click, drag, and drop the stamp anywhere on the page. Mosaic tile-repeats the watermark across the entire page for maximum anti-theft protection.
Can I use both text and image logos as watermarks?
Yes. Jetpap supports customized text stamps (where you can modify font, size, rotation, opacity, and color) as well as image watermarks (where you can upload a PNG, JPG, or SVG logo).
Does watermarking a PDF affect the text searchability?
No. Our watermark tool overlays the stamp on top of the pages as a separate vector or image element. The underlying text remains completely searchable, selectable, and indexable.