---
title: ".csr file — what it is and how to open it"
description: "A .csr file is a Certificate Signing Request. The request you send a certificate authority to get an SSL certificate issued. How to open one on Windows, macOS and Linux, and what to convert it to."
url: https://atoneplace.net/file/csr/
site: "At One Place"
---

# .csr files

**.csr file: Certificate Signing Request**

The request you send a certificate authority to get an SSL certificate issued.

## What opens a .csr file

- **Windows:** Notepad (built in), OpenSSL, Certificate Manager
- **macOS:** TextEdit (built in), OpenSSL, Keychain Access (built in)
- **Linux:** openssl req -text -in file.csr, Text Editor (built in)

## What a .csr file is

A CSR contains your public key and the domain and organisation details you want certified, signed with the matching private key to prove you hold it. You generate it on the server, paste it into the certificate authority, and receive a certificate back — the CSR itself has no further use afterwards. It is base64 text in the same PEM wrapper as certificates, so a text editor or openssl req -text will show what it claims.

## Converting it

A .csr file is commonly converted to .pem, .der or .crt. It is a plain text format, so any text editor can open and edit it directly.

## Details

- **Extension:** .csr
- **Full name:** Certificate Signing Request
- **Category:** Data
- **MIME type:** application/pkcs10
- **Created by:** RSA / IETF (PKCS #10)
- **Format:** Plain text

## Common questions

### How do I open a .csr file?

On Windows use Notepad (built in); on macOS use TextEdit (built in); on Linux use openssl req -text -in file.csr. The request you send a certificate authority to get an SSL certificate issued.

### What is a .csr file?

Certificate Signing Request. A CSR contains your public key and the domain and organisation details you want certified, signed with the matching private key to prove you hold it. You generate it on the server, paste it into the certificate authority, and receive a certificate back — the CSR itself has no further use afterwards.

### Can I convert a .csr file?

Yes. It is usually converted to .pem, .der or .crt, either by exporting from one of the programs listed above or with a format converter.

## Related pages

- [.csv — Comma-Separated Values](https://atoneplace.net/file/csv/)
- [.json — JavaScript Object Notation](https://atoneplace.net/file/json/)
- [.xml — Extensible Markup Language](https://atoneplace.net/file/xml/)
- [.yaml — YAML Data File](https://atoneplace.net/file/yaml/)
- [.log — Log File](https://atoneplace.net/file/log/)
- [.torrent — BitTorrent Metainfo File](https://atoneplace.net/file/torrent/)
- [.dat — Generic Data File](https://atoneplace.net/file/dat/)
- [.vcf — vCard Contact File](https://atoneplace.net/file/vcf/)
- [.sql — SQL Script](https://atoneplace.net/file/sql/)
- [.ics — iCalendar Event](https://atoneplace.net/file/ics/)
- [.sqlite — SQLite Database](https://atoneplace.net/file/sqlite/)
- [.db — Generic Database File](https://atoneplace.net/file/db/)

## Sources

- Media Types Registry — IANA (https://www.iana.org/assignments/media-types/)
- Official vendor product documentation — At One Place (/about/)