Guide5 min read
Why PDF Form Fields Break After Merging
Merged a PDF and the form fields vanished or share one value? Here's the real cause — duplicate field names — and how to merge PDFs safely.
Flatten PDF
Make form fields, comments, and stamps a permanent part of the page. Free, instant, nothing leaves your device.
Drop your PDF here
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Everything you need to flatten a PDF
100% private — nothing uploaded
Flattening happens locally in your browser using pdf-lib and pdf.js. Nothing is sent to a server.
Two flatten modes
Form fields only for a lossless result, or entire document to also bake in comments and stamps.
Keeps text selectable (form mode)
Form-field flattening never rasterizes the page — the rest of your document's text stays selectable and searchable.
Honest about empty PDFs
If there's no form or annotation to flatten, we tell you instead of handing back an unchanged file.
Instant processing
No server round trip — your PDF is rebuilt in seconds, right in the browser.
Three steps to a flattened PDF
- 1
Upload your PDF
Drag and drop your filled-in or annotated PDF onto the page, or click to browse.
- 2
Choose what to flatten
Pick "Form fields only" for a lossless, text-preserving flatten, or "Entire document" to also bake in comments and stamps.
- 3
Flatten and download
Click Flatten PDF — your browser rebuilds a non-editable copy instantly. Download it, nothing is uploaded.
Built for anyone who works with PDFs
Whether you need to lock in a filled application, finalize a signed contract, or archive a document as-is — PixelTools flattens it in seconds, free, with no upload.
Filled application forms
Lock in the values you entered on a job application or intake form so they can't be accidentally changed after submitting.
Signed & annotated documents
Make a signature, comment, or stamp from Sign PDF or Annotate PDF a permanent part of the page before sharing.
Archiving a final version
Turn an interactive PDF into a fixed, non-editable record before filing it away.
Frequently asked questions
Is this tool free?
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Yes, completely free with no limits. No account required.
Is my PDF uploaded to a server?
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No. Flattening happens entirely in your browser using pdf-lib and pdf.js. Your file never leaves your device.
What does "flatten" mean for a PDF?
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It makes form field values, comments, or signatures a permanent part of the page instead of an editable, interactive layer — so the fields can no longer be changed or clicked, and the content looks the same in every viewer.
What's the difference between the two flatten modes?
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"Form fields only" bakes in AcroForm field values and removes the form — lossless, and the page's existing text stays selectable. "Entire document" rasterizes every page to an image, which also flattens comments, highlights, and signature stamps that aren't form fields, but text stops being selectable and the file usually grows.
What if my PDF has no form fields or annotations?
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The tool tells you there's nothing to flatten instead of giving you back an unchanged file — there's no fillable form or annotation layer to bake in.
Will this remove a password from my PDF?
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No. Flatten PDF works on files you can already open. If your PDF is password-protected, use Unlock PDF first.
From the blog
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How to Permanently Redact a PDF
A black box over PDF text doesn't delete it — the text is still copy-pasteable. Redact it for real, free, entirely in your browser.
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Why Compressing a PDF Breaks the Signature
Compressing a signed PDF invalidates its digital signature because compression rewrites file bytes after the signature was created. Here's the fix.
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