Network ports · 443
443 — HTTPS
Port 443 is the default port for HTTPS and for HTTP/3 over QUIC.
Key facts
| Port | 443 |
|---|---|
| Transport | TCP, also UDP for HTTP/3 |
| Service | HTTPS |
| Encryption | TLS |
| Default | Yes, for https:// URLs |
| Also | DoH, WebSocket over TLS |
| Range | Well-known (0–1023) |
TLS first, then HTTP
An HTTPS connection completes a TLS handshake before any HTTP request is sent. The certificate proves the server's identity for the requested hostname, and the negotiated cipher protects the rest of the session. HTTP/2 and HTTP/1.1 both run inside that tunnel.
HTTP/3 is different: it runs over QUIC on UDP 443. Browsers discover it through the Alt-Svc header or HTTPS records, and fall back to TCP if UDP is blocked.
A shared port
Because TLS hides the application protocol until the handshake completes, port 443 carries more than web pages: DNS over HTTPS, WebSocket upgrades, gRPC and some VPN protocols. Firewalls that allow 443 are therefore not limiting traffic to HTTP.
Terminate TLS close to the user, keep certificates renewed automatically, and avoid obsolete protocol versions and ciphers. The port being encrypted does not make a weak configuration safe.
Frequently asked questions
Does HTTP/3 use port 443?
Yes, but over UDP rather than TCP. The port number is the same.
Can other protocols use port 443?
Yes. Anything that can run inside TLS can share the port, including DoH and WebSockets.