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SlimFile.app

Watermark a PDF

Stamp text across every page — CONFIDENTIAL, DRAFT, or anything else. Up to 15 at a time, 25 MB each.

Choose your PDFs

up to 15 at a time.

PDFMax 25 MB each

How it works

  1. Step 1

    Drop a PDF

    Drag up to 15 PDFs onto the page, or browse for them. Each can be up to 25 MB.

  2. Step 2

    Type your text

    Click the watermark button on a file, type what it should say, and pick how see-through it is.

  3. Step 3

    Download it

    The watermark is stamped into every page. Re-applying with different text replaces it rather than stacking a second one on top.

How watermarking works

Every page gets the same grey text, rotated 45° and centred. Changing the text or opacity and applying again always starts fresh from the original file — it never layers watermarks on top of each other.

Diagonal
stamped once across the centre of every page, at 45°
Any text
type up to 200 characters — CONFIDENTIAL, DRAFT, a name, anything
Never stacks
applying it again with new text replaces the old watermark

Why use SlimFile.app for this

  • Replaces instead of stacking

    Apply new text and it swaps out the old watermark rather than piling a second one on top.

  • Stamped on every page

    Your text goes diagonally across each page, in grey, at the opacity you choose.

  • Free, no sign-up

    No account, no email address, no trial that runs out.

  • No watermark

    What you download is clean — nothing added to your file.

  • Deleted within an hour

    Uploads and results are removed automatically about an hour after processing. We never look inside them.

Questions

How do I add "Confidential" or "Draft" to every page of a PDF?
Add the PDF, type the word, set the opacity and apply. It is stamped diagonally across every page, and you can change it again without doubling up.
Can I use my own text?
Yes — type anything up to 200 characters. It is stamped as-is, in grey, diagonally across every page.
What if I want to change the text after applying it?
Open the watermark button again and apply new text or opacity — it replaces what was there before rather than adding a second watermark on top.
Can I watermark a password-protected PDF?
Yes. Enter the password when asked, the same as PDF Slim. It is used once to open the file and is never stored.

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