---
name: "pdf123-compress"
description: "Recompress PDF streams to reduce size. Does not downsample images. Runs the PDF123 \"Compress\" 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: 压缩 PDF, Comprimir PDF, PDF संपीड़ित करें, ضغط PDF, Kompres PDF, Compresser le PDF, Сжать PDF, PDFの圧縮, PDF komprimieren, PDF 압축, Nén PDF, PDF sıkıştır, 壓縮 PDF, Comprimi PDF, บีบอัด PDF, Kompresuj PDF, Стиснути PDF, PDF comprimeren, Mampatkan PDF, Komprimera PDF, Συμπίεση PDF, Компресиране на PDF, Comprimeix PDF, Bana PDF."
compatibility: "Needs curl 7.76+ and outbound HTTPS to pdf123.xyz, or PDFX_API_BASE pointing at a self-hosted pdfx-server."
---

# Compress (PDF123)

Recompress PDF streams to reduce size. Does not downsample images.

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

## When to use

- Fit a PDF under an email or portal upload cap
- Ship a lighter copy while keeping an uncompressed master
- Tighten a naïve office export before attaching it

## 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/compress-pdf" \
  -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

- Will not downsample images; photo-heavy scans may barely shrink
- Password-protected files need the password; API callers run Unlock first
- Broken PDFs may need Repair before compress succeeds
- 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`.