---
title: ".pem file — what it is and how to open it"
description: "A .pem file is a PEM Certificate or Key. A base64 text container for certificates and cryptographic keys. How to open one on Windows, macOS and Linux, and what to convert it to."
url: https://atoneplace.net/file/pem/
site: "At One Place"
---

# .pem files

**.pem file: PEM Certificate or Key**

A base64 text container for certificates and cryptographic keys.

## What opens a .pem file

- **Windows:** Notepad (built in — to read the header), OpenSSL, Certificate Manager (import)
- **macOS:** Keychain Access (built in), TextEdit (built in), OpenSSL
- **Linux:** openssl x509 -text -in file.pem, Text Editor (built in)

## What a .pem file is

PEM files are text, wrapping base64 data between BEGIN and END lines that say what is inside — CERTIFICATE, PRIVATE KEY, PUBLIC KEY. The same format is used for TLS certificates, SSH keys and AWS key pairs, which is why .pem, .crt, .cer and .key often hold identical content. Open one in a text editor to see what it is; treat any file containing a private key as a password and never send it anywhere.

## Converting it

A .pem file is commonly converted to .der, .crt, .pfx or .p12. It is a plain text format, so any text editor can open and edit it directly.

## Details

- **Extension:** .pem
- **Full name:** PEM Certificate or Key
- **Category:** Data
- **MIME type:** application/x-pem-file
- **Created by:** IETF (RFC 7468)
- **Format:** Plain text

## Common questions

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

On Windows use Notepad (built in — to read the header); on macOS use Keychain Access (built in); on Linux use openssl x509 -text -in file.pem. A base64 text container for certificates and cryptographic keys.

### What is a .pem file?

PEM Certificate or Key. PEM files are text, wrapping base64 data between BEGIN and END lines that say what is inside — CERTIFICATE, PRIVATE KEY, PUBLIC KEY. The same format is used for TLS certificates, SSH keys and AWS key pairs, which is why .pem, .crt, .cer and .key often hold identical content.

### Can I convert a .pem file?

Yes. It is usually converted to .der, .crt, .pfx or .p12, 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/)