Return to QUIC, HTTP/2, HTTP/1
HTTP/3 is the third major version of the Hypertext Transfer Protocol used to exchange information on the World Wide Web, complementing the widely-deployed HTTP/1.1 and HTTP/2. Unlike previous versions which relied on the well-established TCP (published in 1974), HTTP/3 uses QUIC (officially introduced in 2021), a multiplexed transport protocol built on UDP.
HTTP/3 uses similar semantics compared to earlier revisions of the protocol, including the same request methods, status codes, and message fields, but encodes them and maintains session state differently. However, partially due to the protocol's adoption of QUIC, HTTP/3 has lower latency and loads more quickly in real-world usage when compared with previous versions: in some cases over four times as fast than with HTTP/1.1 (which, for many websites, is the only HTTP version deployed).
As of September 2024, HTTP/3 is supported by 95% of major web browsers (though not enabled for all Safari users) and 31% of the top 10 million websites. It has been supported by Chromium (and derived projects including Google Chrome, Microsoft Edge, Samsung Internet, and Opera) since April 2020 and by Mozilla Firefox since May 2021. Safari 14 implemented the protocol but it remains disabled by default.