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Flatten PDF

Flatten a PDF form so the answers you typed become part of the page. Checkboxes, dropdown choices and drawn signatures freeze along with them.

Drag & drop your file here, or

How to use

  1. Drop the finished form into the PDF file box, or use Choose file if you'd rather browse.
  2. Press Flatten & download.
  3. The saved copy takes the original name with -flattened on the end, so tenancy.pdf comes back as tenancy-flattened.pdf.
  4. Open the download and click one of the fields you filled. Nothing should happen. That is the test.
  5. Try a checkbox and a dropdown too, since those are the ones readers disagree about.
  6. Put the editable original somewhere safe before you close everything. It is the only way back if an answer changes.

About this tool

Filled a form in a PDF reader and now want the answers nailed down? Flattening a PDF turns each interactive field into ordinary page content. Your typed text is still visible and sits in exactly the same place. It just stops being a field, so clicking it does nothing.

I added this for the minute before you send something back. A leave application with a manager's name in it. A rental agreement where you drew your signature into the last box. Once the fields are frozen, whoever opens the file sees what you saw, whichever reader they happen to use.

Forms like that carry a name and an address, sometimes a bank account number. The flattening runs here on the page through pdf-lib, so the only copy that moves anywhere is the one landing in your downloads folder.

Hand it a PDF with no fields at all and you get back a clean re-saved copy, which is harmless. If the form still needs filling, Fill, Sign & Edit PDF does that part. If what you actually want is a password on the file, Protect PDF (Password) is the one.

A test I ran on a two-page form

For a check I built a two-page rental agreement with nine fields on it: four text boxes, two checkboxes, a dropdown set to 11 months, and two more boxes over on page two. Filled in, the file was 8,674 bytes and pdf-lib counted nine form fields.

After flattening: 8,627 bytes, still two pages, and the field count reads zero. Every typed value is where it was. It is drawn into the page now instead of floating above it in a widget.

Good to know

  • Flattening only goes one way. There is no unflatten step, here or anywhere else, which is the whole reason to keep the original.
  • Text stays selectable. Someone can copy the answers out of the page, and a determined person can paint over them in an editor. If the file needs a password before it opens, Protect PDF (Password) does that job instead.
  • A password-protected PDF stops at the door with an error asking you to unlock it first. Unlock PDF takes the password off, and then this will run.
  • Dynamic XFA forms, the kind a few government and bank portals hand out, are not standard AcroForm fields. Those tend to come back looking exactly as they went in.

Frequently asked questions

How do I make a filled PDF form non-editable?

Flatten it. The tool loads the PDF, draws each field's current appearance into the page, then deletes the field itself. What you end up with is a page that looks the same and has nothing left to click.

What actually changes inside the file?

Every widget gets baked into the page's content stream, and the AcroForm dictionary that listed the fields is emptied out. Load the flattened copy back into pdf-lib and it reports zero fields. That is the whole difference in one line.

Can I undo it if I got an answer wrong?

No. The field is gone from the copy, so the fix is to go back to your original, correct the answer there, and flatten again. Keeping the editable version is worth the trouble for anything you might have to resend.

Will the flattened version look the same in other PDF readers?

That is usually why people flatten in the first place. Readers disagree about how to draw live fields: some tint them, some add a border that was never in the design, and a checkbox tick can render differently from one app to the next. Baked-in content leaves nothing to interpret.

I flattened it and the fields still work. What happened?

Two likely causes. The form is XFA, which pdf-lib cannot flatten, and the run quietly falls through to saving an ordinary copy. Or the PDF had no fields to begin with and you downloaded a re-save. Clicking a field in the download is what tells you which.

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