📐 Flatten PDF

Make filled-in PDF form data uneditable

✓ Free Forever · ✓ No Signup · ✓ No Upload · ✓ Works Offline

🔒 Your documents never leave your device. All processing happens locally in your browser using pdf-lib (client-side). No upload, no server, no tracking.

Features

  • Locks Form Fields — Converts interactive fields into uneditable page content.
  • Print-Ready — Ensures the filled-in version is what prints and shares.
  • 100% Private — Runs in your browser.
  • Fast — Most PDFs flatten in under a second.

How It Works

  1. Upload filled PDF — Drop your file.
  2. Flatten — Click Flatten & Save.
  3. Download — Get the final, locked PDF.

Use Cases

  • Submit a form where recipients shouldn't re-edit
  • Lock in a filled PDF before printing
  • Share final signed forms without accidental edits

Frequently Asked Questions

Can flattening be undone?

No. Keep a copy of the editable original if you might need to change values later.

Does it work on all forms?

On regular PDF forms (AcroForm — what Acrobat, Word, LibreOffice and most official sites make), yes: text boxes, tick boxes, radio buttons, drop-downs and signature boxes are drawn exactly as they look, including values a fill-in script set without drawing them. Dynamic XFA forms (Adobe LiveCycle; outside Adobe Reader their pages only say “Please wait…”) can’t be flattened in a browser — the page says so and how to get a flat copy from Adobe Reader. A form that carries an XFA copy next to its regular fields is flattened from the regular fields.

What happens to hidden fields?

They are left out. A field the form hides isn’t drawn onto the page, and its value isn’t kept anywhere in the file. The notice after flattening says how many there were.

Do Chinese, Japanese or Korean values come out right?

Yes. If the form already drew them, that drawing is kept as it is. If it didn’t (some fill-in scripts leave that to the viewer), your browser draws the text with your system’s fonts and it goes onto the page as a sharp picture of the text: it looks right but can’t be selected or searched. The notice tells you when that happened.

What about digital signatures?

A signature box keeps its look, but a digital signature can’t survive flattening: the file changes, so the signature can no longer be verified. Flatten first and sign afterwards, or keep the signed original.

Upload to server?

No. Runs in your browser.

Notes from Milo 🐨

2026-10-21

I tried this on the kind of form you actually get from an office — one with an empty "sign here" box — and it just failed. Worse things were hiding behind that: values a fill-in script had set came out as the old empty boxes, a hidden field was printed onto the page, a Chinese name broke it, and a LiveCycle form came back as its "Please wait…" page while the FAQ said XFA was supported. Now every field is drawn exactly as a viewer shows it (Chinese and Japanese too), hidden fields are left out and their values are gone from the file, and if a form can't be flattened in a browser, the page says so and how to get a flat copy.

Related Tools

  • 🏷️ Edit PDF Metadata — Edit PDF metadata — title, author, subject, keywords, creator app, producer
  • ✍️ Sign PDF — Sign PDFs with a drawn, typed, or uploaded signature
  • 🔐 Password Protect PDF — Encrypt your PDF with AES-256 — a password to open, plus optional print, copy and edit restrictions
  • 🧹 Sanitize PDF — Strip metadata, scripts, attachments, comments and old revisions before sharing

💬 Bug, idea, or just to say hi? Tell Milo 🐨 · [email protected]