💧 PDF Tools
Add a Watermark to PDF — Free
Stamp text like DRAFT, CONFIDENTIAL, or your company name diagonally across every page of a PDF. Set the opacity, apply it to the whole document, and download — all in your browser, nothing uploaded.
✓ Free forever✓ No upload✓ No signup✓ In your browser
Quick answer: To watermark a PDF, drop your file, type the watermark text (for example CONFIDENTIAL), set the opacity, and click Add Watermark — the text is stamped diagonally across every page and saved into the downloaded PDF, entirely in your browser.
How to Watermark a PDF
1
Add Your PDF
Drop the PDF onto the tool, or click to browse and select it.
2
Type the Text
Enter your watermark text — DRAFT, CONFIDENTIAL, a name, or a date.
3
Set Opacity
Slide to choose how faint or bold the watermark appears.
4
Download
Click Add Watermark, then download the stamped PDF.
Why Use Convertlo?
- 🔒 100% Private — the PDF never leaves your browser
- 🆓 Free forever — no account, no watermark on the tool itself, no limits
- 💧 Every page stamped — the watermark is applied across the whole document
- 🎚️ Adjustable opacity — from a faint tint to a bold overlay
- 📄 Content preserved — the original text and images stay intact underneath
- 📱 Works on mobile — any modern browser, any device
Features
100% Private
No server, no upload — your PDF stays on your device.
Diagonal Stamp
Classic 45° watermark centered on every page.
Opacity Control
Dial the watermark from subtle to strong.
Instant
Applies across all pages in seconds.
No Limit
No page or file-size cap in a session.
Mobile-Ready
Works on iPhone, Android, tablet, and desktop.
Frequently Asked Questions
Yes — completely free, no limits, and no account required. Convertlo runs entirely in your browser using open-source PDF-lib, and it does not add any Convertlo branding to your file.
Yes. The text you enter is stamped diagonally across the center of every page in the document, which is the standard way to mark a whole PDF as DRAFT or CONFIDENTIAL.
No. The watermark is applied locally in your browser. Your files never leave your device, so there is no file-size limit — it is all local processing.
Yes. The opacity slider controls how faint or bold the stamp is, from a light 5% tint up to a heavy 60% overlay, so you can keep the underlying text readable or make the mark dominant.
This tool adds a text watermark. For a logo, first place your logo into a blank PDF page, or use a text label — an image-watermark option is on our roadmap.
No. The watermark is drawn as a semi-transparent layer on top of each page. All original text, images, and formatting remain intact underneath.