# Flatten PDF Online - Lock Form Fields and Annotations

> Free online PDF flattener: lists every form field so you can fill it in first, then turns the form into plain page content, optionally rasterizing each page.

- URL: https://qilingtools.com/en/pdf/flatten
- Category: PDF Tools (https://qilingtools.com/en/pdf)
- Tags: [PDF](https://qilingtools.com/en/tags/pdf), [Documents](https://qilingtools.com/en/tags/document), [Printing](https://qilingtools.com/en/tags/print)
- Last updated: 2026-10-26
- Price: Free, no sign-up
- Privacy: Runs locally in the browser; files are never uploaded

When you send a filled-in PDF form, the recipient can still change the values, and some printers, phone viewers or upload portals even show the fields as blank. Flattening stamps the form fields and annotations onto the page as ordinary content that can no longer be edited. After you upload a file, the tool lists every form field it finds — text boxes, checkboxes, radio buttons, dropdowns and lists — with their current values, and you can fill in or edit them right in the list before flattening, so filling and locking happen in one step. By default only the form fields are flattened and the rest of the page stays vector with selectable text; choose Rasterize every page to burn comments, highlights and stamps into the page as well so no reader can edit anything. Chinese values are written as high-resolution images, never garbled. Everything runs in your browser and files are never uploaded.

## How to use

1. Upload a PDF that contains a form or annotations
2. Review the detected fields and, if needed, tick Fill in or change values and edit them
3. Choose a flatten method and click Flatten & download

## Features

- Detects and lists every form field
- Fill in or edit values before flattening
- Flatten fields only (vector) or rasterize everything
- Chinese values supported, processed locally

## FAQ

### What does flattening a PDF mean?

Flattening converts interactive form fields and annotations into ordinary text and graphics on the page. The document looks the same but can no longer be edited, and it displays identically on every device and printer.

### Which flatten method should I choose?

Usually Flatten form fields only: the file stays small and text remains selectable. Choose Rasterize every page when comments, highlights or stamps must be locked in too, or when nothing may be editable at all.

### Does it work on a PDF without a form?

Yes. With no form fields, choose Rasterize every page to lock comments, annotations and signature stamps into the page.

### Are my files or data uploaded?

No. Everything runs locally in your browser with no network upload, and is discarded when you close the page.

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