How to use Open SSL Checker
- Add a PEM certificate to Open SSL Checker to get started.
- Click Parse certificate — Open SSL Checker processes everything on your device.
- Use the subject, issuer, validity dates and expiry Open SSL Checker produces — nothing was uploaded.
About this tool
There is no server behind Open SSL Checker. Paste a PEM certificate and Open SSL Checker parses the X.509 fields entirely on your device.
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 Open SSL Checker?
Use Open SSL Checker to check your input without installing anything; everything happens client-side.
Do I need an account for Open SSL Checker?
No — Open SSL Checker needs no account, sign-up or installation.
Where is my data processed by Open SSL Checker?
Entirely in your browser — Open SSL Checker keeps your data on your own machine and sends nothing anywhere.
How do I inspect a live site's certificate in Open SSL Checker?
Export the certificate from your browser's padlock as PEM and paste it into Open SSL Checker; it decodes the ASN.1/DER fields entirely on your device.
Does Open SSL Checker work on mobile?
Yes — Open SSL Checker is just a web page and runs on any modern browser, including phones and tablets.