Curated port reference

Port 443: HTTPS / HTTP/3

Port 443 supports HTTPS and HTTP/3 across distinct transports. Review each protocol before writing firewall or monitoring policy.

443TCP

HTTPS

Secure HTTP traffic protected by TLS.

Typical use

Web applications, APIs, reverse proxies, load balancers and encrypted browser traffic.

Traffic direction

Client to server

Security considerations

TLS version, cipher policy, certificate validity and application authorization remain separate security controls.

HTTPTransport Layer SecurityWeb Servers

443UDP

HTTP/3 carried over the QUIC transport protocol.

Typical use

Modern browsers, CDNs, reverse proxies and APIs that negotiate HTTP/3.

Traffic direction

Client to server

Security considerations

UDP 443 needs an explicit firewall path; services should retain a TCP HTTPS fallback and monitor QUIC separately.

HTTPTransport Layer SecurityQuic