Edit PDF
Add Watermark
Overlay diagonal text across every page.
Runs entirely in your browser — the file never leaves this device
100% FREE
No subscription required
COMPLETELY PRIVATE
Your files are never uploaded anywhere
CLIENT-SIDE PROCESSING
All conversions happen in your browser only
YOUR DATA IS YOURS
We process everything locally on your device
Drop your file here
or click to choose from your device
Select fileAbout Add Watermark
Stamp a diagonal text watermark such as CONFIDENTIAL or DRAFT across every page. Arabic watermarks are supported.
How to use Add Watermark
- 1Click "Select file" or drag and drop a PDF into the box above.
- 2Set your text.
- 3Press "Run Add Watermark". The conversion runs on your own device, usually in a few seconds.
- 4Download a watermarked PDF. Nothing is uploaded or stored on any server.
Tips for the best result
- Keep the text short for the biggest, clearest stamp.
Frequently asked questions
Is the Add Watermark tool free?
Yes. It is completely free, with no sign-up, no watermark and no daily limit.
Are my files uploaded to a server?
No. FlashFile processes your files entirely inside your browser, so they never leave your device.
Is there a file size limit?
There is no fixed limit. Files up to about 200 MB work on most computers; very large files depend on your device memory.