Flatten PDF
Lock form fields and annotations into the page.
Runs in your browser
Flatten a PDF form after filling it in, so the answers can't be changed, on your phone or computer. Flattening also makes comments and fields look the same in every viewer, and nothing is uploaded.
How to flatten a PDF online
- 1Select one or more PDFs.
- 2Press the flatten button.
- 3Download the flattened PDF.
Why Sahl PDF?
- Stops filled-in fields from being edited
- Fields and comments look the same in every viewer
- Useful before sending or archiving official forms
- Flatten several files in your browser, no upload
Frequently asked questions
What does flattening a PDF mean?
It turns form fields and annotations into a fixed part of the page — still visible, but no longer editable.
When should I flatten a PDF?
After filling in a form and before sending it, or when fields look different in different PDF viewers.
Can I undo flattening?
Fields can't be made editable again in the flattened file, so keep your original if you might need it.
Is my file uploaded?
No. Flattening happens in your browser and the file never leaves your device.
How do I flatten and compress a PDF?
Flatten the file here first, then run the result through Compress PDF to reduce its size.
How do I flatten a filled-in form before emailing it?
Select the filled form, press flatten and attach the new file. The fields become part of the page and look the same for the recipient.