Flatten PDF
Merge form fields and annotations into the page content permanently.
- 100% Private
- No Limits
- Works Offline
or drag and drop here
Lock in a PDF's form fields and annotations so they become part of the page content and can no longer be edited or filled in. Runs locally in your browser.
How to Use Flatten PDF
- 1
Upload your PDF
Click the upload area or drag in a document with form fields or annotations.
- 2
Flatten and download
Click flatten — your document downloads immediately, no options needed.
Why Choose PurePDF for Flatten PDF
Nothing leaves your device
Flattening happens locally via WebAssembly — your document is never uploaded.
Prevents further edits
Once flattened, form fields can't be accidentally changed by the next person who opens it.
Consistent appearance everywhere
Flattened content renders the same in every PDF viewer, unlike some live form fields.
Common Use Cases for Flatten PDF
Finalize a filled-in form
Lock in your answers before sending a completed form to someone else.
Lock in a signature
Make sure a signature placed on a document can't be moved or deleted.
Prepare for archiving
Flatten interactive elements before storing a document long-term.
Pro Tips for Flatten PDF
- Flattening is one-way — keep a copy of the original if you might need to edit the form again later.
- A PDF with no form fields or annotations is returned unchanged — flattening is safe to run on any file.
- Sign PDF and Fill PDF Form both work well together with Flatten PDF as a final step.
Frequently Asked Questions About Flatten PDF
Will my PDF file be uploaded to a server?
No — nothing is uploaded. This tool runs entirely in your browser via WebAssembly/JavaScript; your file never leaves your device.
Is there a file-size limit, a usage cap, or a hidden fee?
It's free and unlimited, with no watermark and no forced file-size cap — the only real limit is your own device's memory for very large files.
Do I need to create an account or sign up?
No — no account, email, or sign-up is required for any tool. Just start using it.
Can I use this on my phone (iPhone or Android)?
Yes — it works in any modern mobile browser, no app install needed.
Can flattened form fields and signatures be edited later?
No, flattening is a permanent one-way process that integrates form fields and annotations into the page layout; be sure to keep a copy of your original file if future edits are needed.
What happens if I run Flatten PDF on a document that has no interactive form fields?
The document is returned completely intact and unchanged, making it safe to run on any PDF file.