Read an X.509 certificate as JSON online

Inspect an X.509 certificate and get subject, issuer, validity, and key details as structured JSON.

You’ll need
certificate
5 MB max
You’ll get
Details
How long
Under 20s

Need to read who issued a certificate or when it expires? This page turns an X.509 certificate into structured JSON you can search, copy, or feed into other tools.

How to inspect a certificate

  1. Upload a certificate file up to 5 MB.
  2. Press Convert file and review the JSON output.

What you get

A JSON object with subject, issuer, validity window, public key type, extensions, and other fields from the certificate.

When this helps

  • Checking expiry dates before deploying TLS certificates
  • Auditing certificate metadata during security reviews
  • Extracting subject or SAN details without opening a desktop tool
  • Feeding certificate fields into scripts or documentation

Common questions