---
title: Convert Fillable PDF to Locked PDF API
slug: convert-fillable-pdf-to-locked-pdf
url: https://apyhub.com/freedailypro/service/convert-fillable-pdf-to-locked-pdf
provider: FreeDailyPro
tags: [fillable-pdf, locked, pdf, flatten, non-editable]
auth: api_key
version: v1
service_type: sync
endpoints: 1
atoms: 10
mcp: true
---

# Convert Fillable PDF to Locked PDF API

Turn fillable PDFs into locked, non-editable files with one API call. Upload a PDF and get a flattened PDF back. MCP-ready on ApyHub.

## Endpoints

| Method | URL | Description | Atoms |
| --- | --- | --- | --- |
| POST | `https://api.eu.apyhub.com/freedailypro/convert-fillable-pdf-to-locked-pdf/flatten` | What it does Flattens a fillable PDF by taking a PDF file as input and returning a binary PDF file… | 10 |

## Endpoint reference

### Flatten a PDF

`POST https://api.eu.apyhub.com/freedailypro/convert-fillable-pdf-to-locked-pdf/flatten` · 10 atoms · accepts `multipart/form-data` · returns `application/json`

| Parameter | In | Type | Required | Description |
| --- | --- | --- | --- | --- |
| `file` | body | string (binary) | yes | The PDF. Up to 20 MB. |

#### Quickstart

Upload a PDF to flatten its fillable fields into a locked version.

```bash
curl -X POST "https://api.eu.apyhub.com/freedailypro/convert-fillable-pdf-to-locked-pdf/flatten" \
  -H "apy-token: $APY_TOKEN" \
  -F "file=@/path/to/document.pdf"
```

#### What you'll get back

Returns a binary file (`string` with `format: binary`), which is the flattened PDF.

## About

## What it does
PDF Flattening turns a fillable PDF into a locked, non-editable PDF. Send the PDF file in the request body and get a binary PDF back with the form fields flattened into the document.

Use PDF Flattening when you need to preserve what a user entered before archiving, sharing, or sending the file into a workflow that should not allow further edits. It is a practical fit for signed forms, applications, intake sheets, invoices, and other documents where the filled-in content should become part of the page content.

The endpoint accepts one input: `file`, a PDF binary up to 20 MB. The response is the flattened PDF as a binary file, so you can store it, forward it, or attach it to another system without adding another conversion step.

If your application collects PDFs from users and needs a locked final copy, PDF Flattening gives you that output directly from the uploaded document.

## Usage

Base URL: `https://api.eu.apyhub.com` (default region — see
`GET https://apyhub.com/api/public/regions` for the rest).

Authenticate with an ApyHub API key in the `apy-token` header.
Full docs and a live playground: https://apyhub.com/freedailypro/service/convert-fillable-pdf-to-locked-pdf