Add a watermark to a PDF without uploading it
Stamp text like “CONFIDENTIAL”, “DRAFT” or your company name diagonally across every page — saved permanently into the file — without uploading the document anywhere.
No sign-up. No upload. Nothing to install.
How to add a watermark to a PDF
- Open your PDF. Drop the document onto PDFLight. Nothing is uploaded.
- Open the Tools menu. In the toolbar, open Tools and choose the stamp/watermark option.
- Type your watermark. Enter the text you want. It is placed diagonally and semi-transparently across every page.
- Apply and save. Apply the stamp, then Save. The watermark is written into the file itself.
A watermark that travels with the file
Because PDFLight rebuilds the document with the watermark baked in, it stays on every page when the file is emailed, printed or opened elsewhere — it is not a display-only overlay that vanishes on the next machine.
Watermarking is usually about marking a document as confidential, draft or owned — which means the document itself is often sensitive. Every other free PDF tool works the same way: you upload your file, a server you know nothing about processes it, and you trust it to delete the copy afterwards. PDFLight does not. The entire editor is JavaScript running on your own machine, so your document is read into your browser's memory and never travels anywhere. There is no upload endpoint — not as a policy, but as a fact of how the application is built.
You can add page numbers in the same place, and undo the whole thing with Ctrl+Z if you change your mind.
Frequently asked questions
Is the watermark permanent?
Yes. It is written into the PDF, so it stays on every page wherever the file is opened.
Is my document uploaded to watermark it?
No. The stamped PDF is built in your browser. Nothing is sent to a server.
Can I control the watermark text?
Yes — type any text you like. It is placed diagonally and semi-transparently across each page.
Can I add page numbers too?
Yes. The same tool can stamp page numbers, together with or instead of the watermark.
Can I remove it afterwards?
Undo with Ctrl+Z before saving. Once saved into a new file the watermark is part of the document.