SSL/TLS certificate checker

Enter a hostname to see its SSL/TLS certificate details: who issued it, what names it covers, and when it expires.

How to use the ssl/tls certificate checker

  1. Enter a hostname.
  2. Press Check.
  3. Read the issuer, coverage, and days until the certificate expires.

Reading a certificate

This connects to the host on port 443, reads the certificate the server presents, and shows who issued it, the names it covers, and when it expires. An expired certificate makes browsers warn or block visitors, so renew before the "valid until" date — Let's Encrypt automates this on a ~90-day cycle. Also check the site's security headers.

Code & API examples

Use this from the command line or your code. The API is free, GET-only, and returns JSON.

API (curl)
curl "https://vpn.golf/api/tools/ssl?host=example.com"
OpenSSL
echo | openssl s_client -connect example.com:443 -servername example.com 2>/dev/null | openssl x509 -noout -dates

See all endpoints at /api/tools/.

Frequently asked questions

Enter the hostname above — this tool connects to the site, reads its certificate, and shows the exact expiry date and days remaining.

Browsers will warn visitors and may block the site. Certificates must be renewed before their 'valid until' date; Let's Encrypt automates this.
Related tools
HTTP security headers checker DNS lookup tool Open port checker
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