Fill & Flatten PDF Forms

Fill in interactive PDF forms and flatten them so the answers become permanent, non-editable page content, all in your browser. Auto-detects text fields, checkboxes, radio buttons and dropdowns, previews the filled form live, and lets you import/export field data as JSON for bulk or repeat filling. No upload, no signup, no watermark.

Fill & Flatten PDF Forms opens any interactive (AcroForm) PDF, auto-detects every field, and gives you the right control for each one, a text box, a checkbox toggle, a radio choice or a dropdown, with a live preview of the filled page. When you're done, flatten the form to bake the answers permanently into the page so nobody can edit or clear them, or leave it editable if you prefer. You can even export your entries as JSON and re-import them to fill the same form again in seconds. Everything runs in your browser, so filled contracts, applications and tax forms never leave your device.

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PDF Tools
Includes
7 features
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Free · No sign-up
Privacy
Runs in your browser
Fill & Flatten PDF Forms

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Overview

Why flattening a PDF form matters

An interactive PDF keeps your answers in editable form fields that sit on top of the page. That's convenient while you're filling it in, but it means anyone who opens the file can change, clear or tamper with those values, and some PDF viewers render or print form fields inconsistently, so what you see isn't always what the recipient gets. Flattening solves both problems: it merges the field values directly into the page content, turning them into fixed text and marks that can't be edited and that display identically everywhere. This tool fills the fields and then flattens on export, giving you a clean, locked, print-ready document, while still letting you skip flattening if you want to keep the form editable.

Included

Features

01
Auto-detects every AcroForm field: text, checkbox, radio, dropdown and list
02
Live page preview updates as you fill the form
03
Flatten to lock answers into the page so they can't be edited or cleared
04
Import & export field values as JSON for bulk or repeat filling
05
Adjustable text size for form fields
06
Fill without flattening to keep the form editable
07
Works fully offline, files never leave your device
How to use

How to use Fill & Flatten PDF Forms

  1. 01

    Upload a fillable PDF

    Drop an interactive PDF form onto the page. The tool reads it locally and lists every detected field, no upload required.

  2. 02

    Fill the fields

    Type into text fields, toggle checkboxes, pick radio options and choose from dropdowns. The page preview updates so you can see exactly how the finished form looks. Optionally load values from a JSON file to fill everything at once.

  3. 03

    Choose flatten or keep editable

    Turn on Flatten to lock your answers into the page permanently, or leave it off to keep the form fields editable. Adjust the text size if a field needs it.

  4. 04

    Download

    Export your filled (and optionally flattened) PDF instantly. Export your field values as JSON too, so you can refill the same form later without retyping.

Use cases

Common use cases

  • -Complete a job application, tax form or government PDF and lock it so the fields can't be altered.
  • -Fill a contract or agreement and flatten it before emailing, so recipients can't change your entries.
  • -Batch-fill the same form for many people by swapping a small JSON data file each time.
  • -Turn a fillable form into a flat, print-ready PDF that looks identical in every viewer.
  • -Save a half-finished form's data as JSON and reload it later to continue.
  • -Fix a form whose fields won't stick when printed by flattening the values into the page.
Guide

Detailed guide

Every field type, the right control

The tool reads the PDF's AcroForm definition and gives each field a control that matches its type: a text box (single or multi-line) for text fields, a toggle for checkboxes, a picker for radio-button groups, and a menu for dropdowns and list boxes, complete with the exact options defined in the form. A running count shows how many fields you've completed, and a live preview re-renders the page so you can confirm the layout before you download. If a form has no interactive fields at all (for example a scanned document), the tool tells you clearly rather than failing silently.

JSON data in, JSON data out — and total privacy

Filling the same form repeatedly is tedious, so you can export all your field values to a small JSON file and re-import it to refill the form instantly, ideal for recurring paperwork or filling one template for many people by swapping the data. And because every part of the process runs client-side with pdf-lib and pdf.js, your form and its data never leave the browser. Applications, tax documents and signed agreements often contain exactly the kind of personal information you don't want sitting on someone else's server, and here it never does.

FAQ

Frequently asked questions

What does flattening a PDF form do?+

Flattening merges your filled-in values into the page itself, converting editable form fields into permanent, non-editable content. After flattening, the answers can't be changed or cleared, and the form looks identical in every PDF viewer and when printed.

Can I fill the form without flattening it?+

Yes. Just turn off the Flatten option before downloading and the PDF stays interactive, your entries are saved into the fields but remain editable.

Why does it say no fields were found?+

The tool fills interactive AcroForm fields. If a PDF is a scanned image or a 'flat' form with no interactive fields, there's nothing to type into, you'd need a tool that adds text on top instead. You can still flatten and re-download such a file.

Is my form uploaded anywhere?+

No. Everything runs locally in your browser using pdf-lib and pdf.js. Your form and the data you enter are never uploaded, stored or transmitted.

Can I reuse my answers on the same form later?+

Yes. Export your field values as a JSON file, then import that file next time to refill the whole form in one click, great for recurring forms or filling one template for many people.

Is it free and watermark-free?+

Yes, completely free with no signup, no email and no watermark on the exported PDF.

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