How to use SSL TLS Checker
- Paste or load a PEM certificate into SSL TLS Checker.
- Hit Parse certificate and SSL TLS Checker computes the result client-side.
- Read the subject, issuer, validity dates and expiry that SSL TLS Checker lays out for you.
About this tool
Everything SSL TLS Checker does happens on your own device. SSL TLS Checker decodes a pasted PEM certificate by walking its ASN.1/DER structure locally to read subject, issuer, validity window and serial.
The expiry countdown is computed locally, and nothing about the certificate is transmitted. Your input never leaves the page, and no account or install is required.
Frequently asked questions
How do I use SSL TLS Checker?
Use SSL TLS Checker to check your input without installing anything; everything happens client-side.
Is SSL TLS Checker free to use?
Yes — SSL TLS Checker is completely free, with no usage limits.
Is my input private in SSL TLS Checker?
Yes — your input never leaves your device; SSL TLS Checker does all the work in your browser.
How do I inspect a live site's certificate in SSL TLS Checker?
Export the certificate from your browser's padlock as PEM and paste it into SSL TLS Checker; it decodes the ASN.1/DER fields entirely on your device.
Does SSL TLS Checker work on mobile?
Yes — SSL TLS Checker is just a web page and runs on any modern browser, including phones and tablets.