SSL Certificate Checker

Verify SSL/TLS certificates for domains, check validity dates, and inspect certificate details.

Host 443 Ready

HostDomain or IP

Port1 to 65535

Certificate details

Status

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Subject

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Issuer

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Valid From

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Valid To

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Serial Number

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Signature Algorithm

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Public Key Algorithm

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Public Key Length

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TLS Connection

TLS Version

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Cipher Suite

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Subject Alternative Names (SAN)

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Raw response (JSON)

TLS 1.2+ only Instant check Full cert details

How it works

SSL certificates enable encrypted HTTPS connections between browsers and servers. This tool connects to the target server, retrieves the certificate, and validates it against current time and trusted root authorities.

Performs a real TLS handshake to retrieve certificate details.
Checks validity dates (not before / not after) against current time.
Extracts SANs, issuer, public key info, and signature algorithm.

Quick examples

Valid certificate

google.com:443

Status: Valid • Issuer: Google Trust Services

Self-signed / Invalid

self-signed.badssl.com:443

Status: Invalid • Self-signed certificate

Expired certificate

expired.badssl.com:443

Status: Expired • Past validity period

Click "Sample" to load example.com, or try the badssl.com test domains above.

Mini FAQ

What is a SAN?

Subject Alternative Names list all domains the certificate is valid for. Modern certificates use SANs instead of Common Name.

Why check port 8443?

Some servers use alternate HTTPS ports. Enter any port number to check certificates on non-standard ports.

What makes a certificate "invalid"?

Self-signed certs, name mismatches, untrusted issuers, or missing intermediate chains can all cause invalid status.