X.509 Certificate Viewer
View X.509 certificate details: subject, issuer, validity, and algorithms. Paste your data, then click to dissect it. Everything runs on your device, nothing is sent to a server.
Everything runs in your browser. Your data is never sent to our servers.
Example
Example Input
-----BEGIN CERTIFICATE-----…
Example Output
Subject / Issuer / Valid until …
How to Use
- 1Paste your data (PEM/Base64/token) into the Input field.
- 2Click the button (or press Ctrl+Enter) to dissect it.
- 3Read the decoded result in the Output field.
About X.509 Certificate Viewer
An X.509 certificate is a digital document binding an identity (e.g. a domain name) to a public key, signed by a certificate authority (CA). It is the foundation of HTTPS/TLS.
This tool parses a PEM or DER certificate and shows the key fields: subject, issuer, serial number, validity (with an expiry marker), and the key and signature algorithms.
All parsing happens in the browser — your certificate is not uploaded anywhere. To only check the expiry date, use the Certificate Expiration Checker.
FAQ
Are my data or keys sent to a server?
No. X.509 Certificate Viewer runs entirely in your browser using the Web Crypto API and client-side libraries. Your data, passwords, and keys never leave your device.