How to use Mail SSL Checker
- Give Mail SSL Checker a PEM certificate to work from.
- Press Parse certificate to run it locally in your browser.
- Use the subject, issuer, validity dates and expiry Mail SSL Checker produces — nothing was uploaded.
About this tool
There is no server behind Mail SSL Checker. Mail SSL Checker 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. Nothing you enter is uploaded, and it keeps working offline once the page has loaded.
Frequently asked questions
How do I use Mail SSL Checker?
Use Mail SSL Checker to check your input without installing anything; everything happens client-side.
Is Mail SSL Checker free to use?
Yes — Mail SSL Checker is completely free, with no usage limits.
Does Mail SSL Checker upload my data?
No — Mail SSL Checker processes everything locally in your browser, so nothing you enter is uploaded or stored.
How do I inspect a live site's certificate in Mail SSL Checker?
Export the certificate from your browser's padlock as PEM and paste it into Mail SSL Checker; it decodes the ASN.1/DER fields entirely on your device.
Does Mail SSL Checker work on mobile?
Yes — Mail SSL Checker is just a web page and runs on any modern browser, including phones and tablets.