---
name: "pdf123-remove-cert-sign"
description: "Strips digital signature fields from a PDF so it can be edited or re-signed. Runs the PDF123 \"Remove Certificate Signature\" 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: 移除证书签名, Quitar firma de certificado, प्रमाणपत्र हस्ताक्षर हटाएँ, إزالة توقيع الشهادة, Remover assinatura de certificado, Hapus tanda tangan sertifikat, Retirer la signature de certificat, Удалить сертификатную подпись, 証明書署名の削除, Zertifikatsignatur entfernen, 인증서 서명 제거, Gỡ chữ ký chứng chỉ, Sertifika imzasını kaldır, 移除憑證簽章, Rimuovi firma del certificato, ลบลายเซ็นใบรับรอง, Usuń podpis certyfikatem, Зняти підпис сертифіката, Certificaathandtekening verwijderen, Buang tandatangan sijil, Ta bort certifikatsignatur, Αφαίρεση υπογραφής πιστοποιητικού, Премахване на сертификатен подпис, Treu la signatura de certificat, Ondoa saini ya cheti."
compatibility: "Needs curl 7.76+ and outbound HTTPS to pdf123.xyz, or PDFX_API_BASE pointing at a self-hosted pdfx-server."
---

# Remove Certificate Signature (PDF123)

Strips digital signature fields from a PDF so it can be edited or re-signed.

Web version: https://pdf123.xyz/remove-cert-sign · All tools: https://pdf123.xyz/skills/pdf123.md

## When to use

- Clear a signature from a draft so you can edit and re-sign it
- Remove a certification lock that blocks form edits
- Produce an unsigned fixture for a QA workflow

## 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/security/remove-cert-sign" \
  -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

- Destructive: the cryptographic proof is gone for good
- A file with no signature field is returned unchanged, even if it carries a certification entry
- Does not unlock passwords or strip JavaScript
- 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`.

## Authorized use only

Do not use this tool (or any signature-stripping workflow) to falsify an executed agreement or to hide that a document was previously signed. Only alter signatures on documents you are authorized to change.