A New Generation of HTTP Standards
A cluster of Internet standards published today rationalizes and modernizes the definition of HTTP—the application protocol underpinning the web. The work includes updates to, and refactoring of, HTTP semantics, HTTP caching, HTTP/1.1, HTTP/2, and the brand-new HTTP/3. These specifications represent the culmination of efforts within the Internet Engineering Task Force (IETF) and beyond.
The new RFCs to note include:
- HTTP Semantics — RFC 9110: Covers HTTP's overall architecture, common terminology and shared protocol aspects such as request and response messages, methods, status codes, header and trailer fields, message content, representation data, and content codings. Obsoletes RFCs 2818, 7231, 7232, 7233, 7235, 7538, 7615, 7694, and portions of 7230.
- HTTP Caching — RFC 9111: Defines HTTP caches and related header fields controlling response caching. Obsoletes RFC 7234.
- HTTP/1.1 — RFC 9112: A text-based wire format for HTTP, typically used over TCP and TLS. Obsoletes portions of RFC 7230.
- HTTP/2 — RFC 9113: Binary framing format with streams supporting concurrent requests and responses. Message fields can be compressed using HPACK. Typically used over TCP and TLS. Obsoletes RFCs 7540 and 8740.
- HTTP/3 — RFC 9114: Binary framing optimized for the QUIC transport protocol, with message fields compressed using QPACK.
- QPACK — RFC 9204: A variation of HPACK compression optimized for QUIC.
For Cloudflare, the publication is largely ceremonial: QUIC version 1 and HTTP/3 were enabled for all customers on May 28, 2021, using the final "h3" identifier matching RFC 9114. This analysis examines HTTP traffic across the Cloudflare network over the 12 months ending May 7, 2022, including version usage by major browsers, search engine bots, and social media crawlers. Cloudflare bot scores were used to isolate "likely human" browser traffic from "likely automated" bot traffic.
Overall Protocol Mix
HTTP/2 continues to dominate request traffic across Cloudflare's customer base. After remaining fairly consistent through 2021, HTTP/2 request volume rose approximately 20% heading into 2022. HTTP/1.1 traffic stayed flat over the year, aside from a slight dip in early December. HTTP/3, which initially trailed HTTP/1.1, surpassed it in early July and grew steadily, roughly doubling over the twelve-month period.
Browser Adoption of HTTP/3
Among browser families, Google Chrome leads HTTP/3 usage by a substantial margin, far outpacing other browsers in daily aggregate request volume.
Removing Chrome from the picture reveals trends across the remaining browsers. Microsoft Edge, built on the Chromium engine, closely mirrors Chrome's pattern. Mozilla Firefox enabled production HTTP/3 support by default in version 88 at the end of May 2021, and the adoption of that update shows clearly as HTTP/3 request volume from Firefox grew rapidly in the following month. Apple Safari's HTTP/3 traffic increased gradually through April, likely reflecting users enabling the experimental feature in production releases or running Technology Preview builds. Safari's HTTP/3 traffic subsequently dropped over the last couple of months, though most recent observations indicate a recovery.
A clear weekly cycle is visible in traffic from Chrome, Edge, and Firefox—indicating heavier usage during the work week—but this pattern is notably absent from Safari usage.
Across all surveyed browsers, Chrome accounts for approximately 80% of the HTTP/3 requests seen by Cloudflare. Edge contributes around another 10%, Firefox just under 10%, and Safari the balance.
Looking at how the HTTP version mix shifted over the year, trends are broadly similar across Chrome, Firefox, and Edge, though the absolute percentages differ. These changes are largely customer-driven, reflecting modifications in Cloudflare customer configurations rather than browser feature rollout. The most notable shifts include an increase in HTTP/3 traffic during the last week of September and a decrease in HTTP/1.1 at the beginning of December. Safari shows the December HTTP/1.1 drop but not the September HTTP/3 increase, a distinction expected to disappear once Safari supports HTTP/3 by default.
Search Engine Bots
Although Google announced in 2014 that it would consider HTTPS usage as a ranking signal, the major search engines do not appear to currently consider support for the latest HTTP versions in their indexing decisions. Still, the protocol choices of their crawlers reveal interesting patterns.
GoogleBot, despite Google's early involvement in QUIC development and HTTP/3 integration into Chrome, remains predominantly an HTTP/1.1 crawler. Usage of HTTP/2 has grown over the last six months, gradually approaching HTTP/1.1 request volumes. Requests from GoogleBot over HTTP/3 have remained extremely limited over the past year.
Microsoft's BingBot likewise shows near-zero HTTP/3 usage. However, unlike GoogleBot, BingBot prefers HTTP/2, with a wide margin established in mid-May 2021 and maintained consistently across the rest of the year.
Social Media Bots
Major social platforms deploy custom crawlers to fetch metadata for shared content, improve language models, or index site content. Their protocol preferences vary considerably.
Facebook supports HTTP/3 on its main website, but the FacebookBot crawler does not appear to offer it. Over the last year, roughly 60% of FacebookBot requests used HTTP/1.1, with the balance over HTTP/2. Heading into 2022, HTTP/1.1 preference trended lower—dropping from near 80% to just under 50% during the fourth quarter—before abruptly reversing and growing back to over 70% in early February, for reasons that remain unclear.
TwitterBot shows virtually no HTTP/3 usage but displays a strong, consistent preference for HTTP/2, which accounts for 75-80% of its requests, with the balance over HTTP/1.1.
LinkedInBot has been firmly committed to HTTP/1.1 over the past year, aside from a brief anomalous period of HTTP/2 usage last June. However, since mid-March, it has tentatively begun exploring other versions, with roughly 5% of requests now over HTTP/2 and about 1% over HTTP/3.
Observations on Adoption
The publication of HTTP/3 as RFC 9114 is welcome, particularly given how steadily browsers have enabled the protocol by default, allowing end users to benefit from HTTP/3 whenever available. Cloudflare's network has seen continued growth in HTTP/3's share of traffic, reflecting ongoing customer interest in enabling it. In contrast, the major search and social platforms continue to run their crawlers on aging HTTP versions. Understanding how these platforms select particular HTTP versions, and exploring the advantages HTTP/3 could offer them, remains an open avenue for collaboration.
Country- and ASN-level statistics on HTTP/3 and QUIC adoption are available on Cloudflare Radar. Further protocol innovation continues apace: the IETF is already building on HTTP/3 and QUIC foundations with efforts such as MASQUE and WebTransport, while the QUIC Working Group has adopted new work on QUIC version 2 and a Multipath Extension to QUIC.
