Fill, Sign & Flatten a PDF — in One Tool

Three steps, one tool, zero uploads. Here's exactly how it works.

One Tool Does All Three Steps

Filling out a form, signing it, and locking it against further edits sound like three separate jobs — but PDFree's Fill tool handles all three in a single pass:

  • Fill — enter text into form fields, check boxes, and pick dropdown values. Detected automatically from the PDF's AcroForm structure.
  • Sign — the same tool includes a signature pad: draw, type, or upload an image of your signature, then place it on the page.
  • Flatten — a "Flatten fields" checkbox, checked by default, bakes every value and the signature permanently into the page and removes the interactive form structure before the file downloads.

Because flattening happens by default in the same download, most people never need a second tool at all. The standalone Flatten tool still exists for one specific case: you already have a filled PDF from somewhere else (or you unchecked the flatten option earlier) and now want to lock it after the fact.

The Full Walkthrough

1
Fill in the form
Open pdfree.io/fill/ and upload your PDF. Detected fields — text boxes, checkboxes, dropdowns — become clickable. Fill in your information.
2
Add your signature
In the same tool, open the signature pad and choose Draw, Type, or Upload. Place it on the signature line.
3
Download — already locked
Leave "Flatten fields" checked (it's on by default) and click download. Your answers and signature are baked into the page as final content — nobody, including you, can edit the fields on this file anymore. One click, one file, done.

Need to keep it editable a bit longer? Uncheck "Flatten fields" before downloading. You'll get a PDF where the fields are still filled in but remain editable — useful while you're still double-checking entries. Run it back through the Fill tool (or the standalone Flatten tool) once you're ready to lock it in. Flattening itself isn't reversible, so keep an unflattened copy until you're certain everything is correct.

When Flattening Actually Matters

📄
Contracts and agreements

Once both parties sign, neither side should be able to quietly change a term afterward.

🧾
Government or HR forms

Submitted intake forms and applications should reflect exactly what was submitted, permanently.

✅
Consent and waiver forms

A signed waiver that can still be edited defeats the purpose of having it signed at all.

Frequently Asked Questions

Do I have to use two separate tools for this?

No. PDFree's Fill tool fills the form, places your signature, and flattens the result into a locked, non-editable PDF — all in one download. The separate Flatten tool only exists for the rare case where you already have a filled PDF from somewhere else and need to lock it after the fact.

Why flatten a PDF after filling and signing it?

Without flattening, a filled-in form's fields are still editable — anyone who opens it can change what you typed or move your signature, even after saving. Flattening bakes every value into permanent page content and removes the interactive form structure.

Can I keep an editable copy instead of flattening?

Yes. The Fill tool shows a "Flatten fields" checkbox, checked by default. Uncheck it before downloading if you want the output to remain an editable form — useful if you need to come back and adjust an answer later.

Is flattening reversible if I made a mistake?

No — once flattened, the original interactive fields are gone from that file. If you're not sure everything is correct yet, uncheck "Flatten fields" first and review the editable download before locking it in.

Does this workflow require uploading my document anywhere?

No. The Fill tool runs entirely in your browser — your document never leaves your device at any step of filling, signing, or flattening.

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