Flatten PDF
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Flattening a PDF means converting its interactive form fields into static page content, so the filled-in values become a permanent part of the page and can no longer be edited. The page's appearance is unchanged; only the editable form layer is removed.
At a Glance
1 Credit
Per Run
On-Device
Processing
Form Fields
Target
25 MB
Free File Limit
Key Facts
LittlePDF Flatten PDF merges a PDF's interactive AcroForm fields into static page content using pdf-lib's form flatten, run entirely in the browser.
Flattening locks filled values so they can no longer be edited while preserving the page's appearance; the original file is left unmodified.
The flatten runs client-side, costs 1 credit, and works on files up to 25 MB free or 500 MB on Pro. It is not a compression tool and provides no guaranteed size reduction.
How to Flatten PDF in 3 Steps
Drop the PDF with form fields into the upload area.
Leave the form-fields option on, then start the process.
Click the process button and the flattened PDF downloads to your device.
Why Flatten PDF with LittlePDF?
Lock a filled-in form so the values become part of the page and cannot be edited in a reader.
The visual appearance is preserved; only the editable form layer is removed.
Your original stays fillable on your device while you download a separate flattened copy.
Everything runs in your browser with pdf-lib, so the form is never uploaded to a server.
Features
Form-Field Flattening
Interactive AcroForm fields are merged into the page through pdf-lib, so the filled values become static content. This is the core of finalizing a completed form before you share it.
Appearance Preserved
Flattening locks the values in without changing how the page looks. What you see in the filled form is what stays on the page after it is flattened.
On-Device and Non-Destructive
The flatten runs locally in the browser and writes a new file, leaving the original untouched. You keep a fillable copy and download a flattened one, with nothing uploaded.
Frequently Asked Questions
Last updated: June 2026