---
name: "pdf123-flatten"
description: "Flatten form fields or the whole document into static content. Runs the PDF123 \"Flatten\" tool (pdf123.xyz) over its REST API with curl, no account needed. Use when the user wants this done to their file. Also known as: 展平 PDF, Aplanar PDF, PDF समतल करें, تسطيح PDF, Achatar PDF, Ratakan PDF, Aplatir le PDF, Свести PDF, PDFの平坦化, PDF abflachen, PDF 평면화, Làm phẳng PDF, PDF düzleştir, Appiattisci PDF, ผสาน PDF, Spłaszcz PDF, Звести PDF, PDF afvlakken, Platta ut PDF, Ισοπέδωση PDF, Сплескване на PDF, Aplana PDF, Bana fomu."
compatibility: "Needs curl 7.76+ and outbound HTTPS to pdf123.xyz, or PDFX_API_BASE pointing at a self-hosted pdfx-server."
---

# Flatten (PDF123)

Flatten form fields or the whole document into static content.

Web version: https://pdf123.xyz/flatten · All tools: https://pdf123.xyz/skills/pdf123.md

## When to use

- Freeze filled form appearances before an archive
- Turn review markup into page content
- Stop a viewer from showing editable widgets

## Run it

Replace the sample file names and values with the user's, then run:

```bash
API="${PDFX_API_BASE:-https://pdf123.xyz}"
curl -sS --fail-with-body -X POST "$API/api/v1/misc/flatten" \
  -F "fileInput=@input.pdf" \
  --output-dir "pdf123-output/$(date +%Y%m%d-%H%M%S)" --create-dirs -OJ -w '%{filename_effective} %{content_type}\n'
```

## Inputs

Everything is `multipart/form-data`. The command above already sends each field with its default; keep them all and change only the values the user asked for, since some endpoints reject a missing optional field.

| Field | Type | Required | Default | Notes |
| --- | --- | --- | --- | --- |
| `fileInput` | file | yes | | .pdf (one file) |

## Result

curl saves the result in a new `pdf123-output/<timestamp>/` directory under the server's file name and prints its path and content type. Several output files come back as one ZIP. Tell the user where the file is.

## Limits

- No forms-only mode
- Can invalidate signatures
- Password-protected files need the password; API callers run Unlock first
- Upload limit on this website: 500 MB per file, sent in chunks above about 95 MB. A single direct API request body is capped at 100 MB.

## Errors

- A non-zero curl exit means the request failed. The saved file then holds `application/problem+json`; read it and report its `detail` to the user instead of retrying blindly.
- `413`: the upload exceeds 100 MiB. `429`: wait for `Retry-After` seconds, then retry once.
- Send `X-API-KEY: $PDFX_API_KEY` only if the user has a PDF123 API key; anonymous calls work without it.

## Privacy

Files are uploaded to the API host, processed, and deleted once the response is sent. For confidential files, ask before uploading, or use a self-hosted server via `PDFX_API_BASE`.