Flatten PDF — lock form fields and annotations, free and private

Flatten a PDF so completed form fields, signatures, and annotations become static content that can no longer be edited or changed. Flattening runs entirely in your browser, so the document is never sent to our servers.

How to flatten a PDF

  1. Drop your PDF into the box above, or click to choose a file.
  2. Pick what to flatten — form fields, annotations, or both.
  3. Click Flatten — processing happens locally, in your browser.
  4. Optionally re-render pages to images for an extra-locked result.
  5. Download the flattened PDF. The original is never uploaded to our servers.

What it does

  • Flattens form fields and annotations into permanent, static content
  • Keeps filled-in values, checkboxes, and signatures exactly as they look
  • Optional re-render to images so nothing underneath stays editable
  • No watermark, no sign-up, nothing sent to our servers

Common uses

  • Locking a completed application or intake form before you send it back
  • Making sure a signed agreement can't be altered after the fact
  • Stopping annotations and comments from being moved or deleted by a recipient

Is it private?

Yes. Unlike most "flatten PDF online" tools, PaperFit never uploads your file to our servers. Flattening happens on your own device using your browser, which matters because the forms you flatten are often filled with personal details — a signed contract, a tax or benefits form, a medical intake sheet. Those stay with you the whole time. You can confirm it: open your browser network tab and watch — your file is never uploaded to our servers while you flatten.

Frequently asked questions

Are my files uploaded to a server?

No. Flattening runs 100% in your browser. Your PDF is never sent to our servers.

What does flattening actually do?

It bakes interactive content — form fields, checkboxes, signatures, and annotations — into the page as static content, so the values stay visible but can no longer be edited.

What's the difference between flattening and re-rendering to images?

Standard flattening keeps the text and fields as fixed page content. The optional re-render turns each page into an image, which fully locks everything but makes the text non-selectable.

Can a flattened PDF be un-flattened or re-edited?

Standard flattening makes fields static so they can't be filled in again, though the underlying text may still be selectable. Use the re-render to images option if you need the strongest lock.

Is there a file size limit, and is it free?

It's free with no account, and you can flatten PDFs up to 200 MB. If your file is password-protected, unlock it first with the Protect tool before flattening.

Does it work on my phone?

Yes. It runs in any modern mobile browser, though very large files flatten faster on a desktop or laptop.

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