HTTP/3 maps HTTP onto QUIC instead of TCP.

QUIC runs over UDP but implements reliable delivery, encryption, and connection management itself. Its streams are independent. If a packet for one stream is lost, unrelated streams can continue.

QUIC includes TLS security and can reduce connection setup work. It can also keep a connection alive when a device changes networks, because the connection is not identified only by one IP address and port pair.

You normally do not rewrite application code for HTTP/3. Your hosting platform, CDN, server, and browser negotiate it. Methods, status codes, URLs, and headers remain the same.

Use the Network panel’s protocol column to see which version a request used.