Announcing Support for HTTP/2 Server Push

In November 2015, Cloudflare rolled out support for HTTP/2, which has since been adopted by more than 88k of the Alexa top 2 million websites. Today, over 70% of sites using HTTP/2 are served via Cloudflare. One key feature of HTTP/2 is multiplexing, which allows multiple HTTP requests to share a single TCP connection, improving performance compared to HTTP/1.1. In addition to multiplexing, HTTP/2 also introduces new features such as Header Compression and Server Push. Since February, Cloudflare has been testing and deploying HTTP/2 Header Compression, resulting in an average 30% reduction in header size for all clients using HTTP/2. Server Push is another major feature of HTTP/2 that enables websites and APIs to speculatively deliver content to the web browser before the browser sends a request for it. This can significantly improve website performance if used judiciously, as it reduces the number of round trips required between the client and server. All Cloudflare customers using HTTP/2 now have Server Push enabled by default. To leverage this feature effectively, users need to add specially formatted Link headers to their responses, indicating which assets should be pushed. Some best use cases for HTTP/2 Server Push include uncacheable content, all assets on a requested page, and the most likely next page. While several browsers currently support Server Push, more tools are expected in the future to help users make educated decisions about its usage. Cloudflare is also looking forward to hearing from customers who experiment with this feature as they continue monitoring HTTP/2 development efforts.