# SSL Certificate Checker

URL: https://tools.otaku-dojo.com/en/ssl-checker
Updated: 2026-10-03

The SSL Certificate Checker completes a TLS handshake on port 443, reads the certificate the server presents and tells you how many days remain before it expires, whether it is issued by a trusted certificate authority, whether the hostname matches, which TLS version is used, and every domain listed in Subject Alternative Names. Untrusted or expired certificates are still read, with the reason shown.

## How to use the SSL Certificate Checker

1. Enter a domain (e.g. example.com) or full URL and press "Check".
2. The top shows days remaining, trust, hostname match and TLS version.
3. "Certificate" lists the issuer, validity period and covered domains.
4. Fewer than 30 days remaining shows yellow; fewer than 14 days or expired shows red.

## Specs & key facts

- **Checks**: Days remaining, validity period, issuer, subject, SAN list, TLS version
- **Verification**: Certificate chain and hostname against trusted CAs
- **Untrusted certificates**: Still read, with the failure reason (self-signed, expired, incomplete chain)
- **Ports**: 443 by default; enter example.com:8443 for 8443
- **Limits**: Public URLs only, 20 checks per minute
- **Price**: Free, no sign-up

## Examples: Check a Let's Encrypt certificate

```text
otaku-dojo.com
```

→

```text
Days remaining: 31
Issuer: Let's Encrypt · YR1
Trusted: yes | Hostname: match | TLSv1.3
Domains: otaku-dojo.com, www.otaku-dojo.com
```

## FAQ

### My browser says the site is secure but the tool says untrusted. Why?

Usually the server is not sending the full intermediate certificate chain. Browsers may fill the gap from cache, but other clients and some phones fail. Configure your server with the full chain certificate.

### What is the difference between SSL and TLS?

TLS is the successor to SSL; SSL 3.0 and TLS 1.0/1.1 are deprecated. "SSL certificate" is still the common name, but sites should use TLS 1.2 or 1.3.

### Can I check ports other than 443?

Ports 443 and 8443 are supported — enter example.com:8443. Other ports are blocked for security.