How to use Certificate Checker
- Paste the text you need to check into the input box.
- Set Paste a PEM certificate (BEGIN/END lines) so the output fits your use case.
- Certificate Checker updates the output automatically as you type.
- When it looks right, Copy to save it.
About this tool
There is no server behind Certificate Checker. Certificate Checker parses the X.509 fields of a certificate you paste, locally.
Nothing about the certificate is transmitted. Nothing you enter is uploaded, and it keeps working offline once the page has loaded.
Frequently asked questions
How do I use Certificate Checker?
Use Certificate Checker to check your input without installing anything using the Paste a PEM certificate (BEGIN/END lines) control; everything happens client-side.
Does Certificate Checker cost anything?
No — Certificate Checker is completely free, with no sign-up and no hidden limits.
Does Certificate Checker upload my data?
No — Certificate Checker processes everything locally in your browser, so nothing you enter is uploaded or stored.
How do I inspect a live site's certificate with Certificate Checker?
Export the certificate from your browser's padlock as PEM and paste it into Certificate Checker; it decodes the fields locally.
Does Certificate Checker work offline?
Once the page has loaded, Certificate Checker keeps working with no network connection.