Nginx 1.25.0 Released: Experimental HTTP/3 Support

What happened

Nginx 1.25.0 was released on May 23, 2023, according to the official Nginx CHANGES log. As the opener of a new mainline branch, its changelog entry listed a single, significant feature: experimental HTTP/3 support.

Experimental HTTP/3

HTTP/3 is the third major version of the HTTP protocol, built on QUIC, a UDP-based transport that reduces connection-setup latency and avoids head-of-line blocking at the transport layer. Bringing experimental HTTP/3 into a mainline Nginx release let the enormous base of Nginx operators begin testing the protocol directly in the server they already run, rather than through a separate build.

HTTP/2 refinements in 1.25.x

Subsequent releases in the branch refined HTTP/2 handling. Nginx 1.25.1, released on June 13, 2023, introduced an http2 directive to enable HTTP/2 on a per-server basis and deprecated the http2 parameter of the listen directive, while removing HTTP/2 server push support and dropping the deprecated ssl directive. Nginx 1.25.3 later improved detection of misbehaving HTTP/2 clients.

Ongoing HTTP/3 work

Across the 1.25.x branch, Nginx continued to deliver bug fixes and improvements in HTTP/3, including path MTU discovery and additional cipher-suite support in 1.25.2, as the QUIC-based implementation matured toward the stability reflected in later stable branches.

Why it mattered

Nginx 1.25.0 was a landmark for the web's transport layer. By shipping experimental HTTP/3 in mainline, Nginx put the QUIC-based protocol in front of a huge operator base, accelerating real-world testing and adoption of HTTP/3 across the internet's most-used web server.

Related on Skillo

See also: Nginx 1.27.0's QUIC security fixes.

Sources

• nginx CHANGES log (nginx.org)

Published date reflects the original event date (2023-05-23). This article is original Skillo editorial written from the sources above; facts were verified in September 2026.