.pem · application/x-pem-file
What is a .pem file?
PEM Container
Got a .pem file right now?
Our Certificate Decoder reads it in your browser — no upload, no install.
Open the Certificate Decoder →About the format
A .pem file is Base64-armoured cryptographic material — the text format with -----BEGIN SOMETHING----- and -----END SOMETHING----- fences. The 'something' is the real story: CERTIFICATE (public, shareable), CERTIFICATE REQUEST (a CSR awaiting signature), PRIVATE KEY or RSA PRIVATE KEY (secret — this is the crown jewels), ENCRYPTED PRIVATE KEY (secret, password-protected), or PUBLIC KEY. One .pem can hold several blocks: fullchain.pem from Let's Encrypt is your certificate plus intermediates; some exports bundle certificate and private key together, which makes the file as sensitive as the key. That's the habit to build with .pem files: glance at the BEGIN lines before doing anything else, because they tell you whether you're holding something public or something that must never leave the server. PEM is the lingua franca of openssl, web servers and everything Unix-adjacent; Windows tools accept it too, though .pfx is the native Windows bundle format.
How to open a .pem file
Windows
- WhyCrashed Certificate Decoder (browser — paste or drop)
- any text editor (to see the block types)
- openssl
macOS
- openssl
- text editor
Linux
- openssl
- text editor
Is a .pem file dangerous?
Depends entirely on its blocks: certificates are public; a PRIVATE KEY block is a secret worth protecting like a password.
Related file types
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