How to use OpenSSL Test Cert
- Paste or load a PEM certificate into OpenSSL Test Cert.
- Press Parse certificate to run it locally in your browser.
- Review the subject, issuer, validity dates and expiry shown below.
About this tool
OpenSSL Test Cert runs entirely in your browser. OpenSSL Test Cert decodes a pasted PEM certificate by walking its ASN.1/DER structure locally to read subject, issuer, validity window and serial.
To check a live site, export its certificate from the browser padlock as PEM and paste it here. Your input never leaves the page, and no account or install is required.
Frequently asked questions
What is OpenSSL Test Cert for?
Use OpenSSL Test Cert to check your input without installing anything; everything happens client-side.
Does OpenSSL Test Cert cost anything?
No — OpenSSL Test Cert is completely free, with no sign-up and no hidden limits.
Where is my data processed by OpenSSL Test Cert?
Entirely in your browser — OpenSSL Test Cert keeps your data on your own machine and sends nothing anywhere.
How do I inspect a live site's certificate in OpenSSL Test Cert?
Export the certificate from your browser's padlock as PEM and paste it into OpenSSL Test Cert; it decodes the ASN.1/DER fields entirely on your device.
Does OpenSSL Test Cert work offline?
Once the page has loaded, OpenSSL Test Cert keeps working with no network connection.