PEM Decoder
Paste a PEM-encoded certificate, CSR or key to see what it contains: subject and issuer, validity, alternative names, extensions, key type and size, and fingerprints. Decoded in your browser.
- Runs in your browser
- Free to use
About this tool
PEM files are base64 wrappers around DER-encoded ASN.1 structures, unreadable without a tool. The PEM Decoder parses them in your browser and lists what matters: for a certificate the subject, issuer, serial, validity with days left, public key type and size, signature algorithm, every extension (subject alternative names, key usage, basic constraints, authority info access, CRL URLs) and the SHA-256 and SHA-1 fingerprints; for a CSR the subject, key and requested extensions; for keys the algorithm, size or curve, without ever displaying private material. Paste a whole chain to decode each certificate in turn.
Need to create one? Use the SSL Certificate Generator; to inspect a live site use the SSL Certificate Check.
How to use it — quick steps
- 01
Enter the pem data
Type or paste the pem data in the field above, for example -----BEGIN CERTIFICATE-----.
- 02
Press "Decode PEM"
Press "Decode PEM" or Ctrl + Enter. The result appears instantly below the form. Results can be copied.
- 03
Read the result
It appears in the dark panel under the form instantly. Every block has [copy] and other actions.
Key features of this tool
Nothing leaves your browser
The processing is plain JavaScript that runs on your device: the text you paste is never uploaded to our servers or to anyone else.
Instant results
Results appear the moment you press the button, even for long inputs, and every block has copy and download actions.
Works everywhere
No installation, no account and no limits: the tool works on desktop and mobile, in any modern browser, as often as you like.
Frequently asked questions
Which PEM types are supported?
CERTIFICATE (X.509 v1-v3), CERTIFICATE REQUEST (PKCS#10), PUBLIC KEY, RSA PUBLIC KEY, PRIVATE KEY (PKCS#8), RSA PRIVATE KEY, EC PRIVATE KEY and ENCRYPTED PRIVATE KEY; several blocks can be pasted at once, for example a full chain.
Is my private key safe to paste here?
The decoding runs in your browser and the key never leaves it; the tool also shows only the key type and size, never the key material. Still, prefer the public certificate when you only need its details.
What is a fingerprint?
The SHA-256 or SHA-1 hash of the DER-encoded certificate, used to pin or compare certificates; it is computed locally.
Can it verify the certificate?
No, it decodes the structure; it does not check the signature or the chain. Use the SSL Certificate Check for a live server.
Are my files or data uploaded?
No. The tool is plain JavaScript that runs in your browser; the files or data you provide here are never uploaded to our servers.