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SSL Certificate Decoder: Read a PEM Certificate

For admins, DevOps and security engineers checking a certificate. Paste the PEM text to see who it was issued to, by whom, until when and for which names.

FreeRuns in your browserNothing uploadedNo sign-up neededAll 15 tools in the Security Toolbox
Keep this resultSign in to email it to yourself or save it to your profile. The tool itself never needs an account.

Exams

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How to use

How to use the SSL Certificate Decoder

  1. Paste the certificate, from -----BEGIN CERTIFICATE----- to the END line; a chain works too.
  2. Click Decode.
  3. Check Valid to, the SAN names and the issuer.
  4. Compare the SHA-256 fingerprint if you need to match a certificate exactly.
Worked example

An example, step by step

You enter

The sample certificate for www.example.com

The tool shows

Subject and issuer C=IN, O=Example Org, CN=www.example.com (self-signed), valid 8 October 2026 to 9 November 2027 (397 days), SAN www.example.com and example.com, key EC P-256, ECDSA with SHA-256, SHA-256 fingerprint 51:A4:53:4F:...:4F:FE

FAQ

Questions about the SSL Certificate Decoder

How do I check when an SSL certificate expires?

Paste it here and read Valid to, or run openssl x509 -in cert.pem -noout -enddate. The decoder also shows how many days are left.

Is it safe to paste a certificate here?

Yes. A certificate is public and it is decoded in your browser, not uploaded. Never paste a private key anywhere: the tool refuses it.

What is the SAN in a certificate?

Subject Alternative Name: the list of domain names (and IPs) the certificate is valid for. Browsers check the SAN, not the CN.

Is the SSL Certificate Decoder free and private?

Yes. It is free, needs no sign-up and runs entirely in your browser, so what you type is not uploaded. You only sign in if you want to email a result to yourself or save it to your CareerByteCode profile.

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