How to use HTTPS Checker
- Give HTTPS Checker a PEM certificate to work from.
- Click Parse certificate — HTTPS Checker processes everything on your device.
- Use the subject, issuer, validity dates and expiry HTTPS Checker produces — nothing was uploaded.
About this tool
HTTPS Checker is a static, client-side tool with no backend. HTTPS 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. It behaves the same on desktop and mobile, with nothing stored remotely.
Frequently asked questions
What does HTTPS Checker do?
HTTPS Checker lets you check your input right in the browser, with the result shown instantly and nothing uploaded.
Is HTTPS Checker free to use?
Yes — HTTPS Checker is completely free, with no usage limits.
Where is my data processed by HTTPS Checker?
Entirely in your browser — HTTPS Checker keeps your data on your own machine and sends nothing anywhere.
How do I inspect a live site's certificate in HTTPS Checker?
Export the certificate from your browser's padlock as PEM and paste it into HTTPS Checker; it decodes the ASN.1/DER fields entirely on your device.
Can I use HTTPS Checker without a connection?
Yes — after the first load HTTPS Checker runs entirely offline.