HTTP/2 vs HTTP/3 Comparison
Compare HTTP/1.1, HTTP/2, and HTTP/3 protocols side by side with interactive filtering, color-coded ratings, and a migration guide.
About This Tool
The HTTP Protocol Comparison tool provides a comprehensive, interactive side-by-side comparison of the three major HTTP protocol versions: HTTP/1.1 (RFC 2616, later revised in RFC 7230–7235), HTTP/2 (RFC 7540, revised as RFC 9113), and HTTP/3 (RFC 9114). It covers every significant difference across eight categories: Transport Protocol, Connection, Multiplexing, Header Compression, Server Push, Security, Performance, and Browser Support.
Each feature is color-coded to indicate whether the protocol handles it well (green), adequately (yellow), or poorly (red), making it easy to see at a glance how the protocols compare. You can toggle individual protocol columns on or off to focus on a specific comparison, such as HTTP/2 vs HTTP/3 only.
This tool runs entirely in your browser. No data is sent to any server, and there are no third-party dependencies. It is designed for web developers, DevOps engineers, and anyone planning a protocol upgrade or studying for technical interviews.
For related topics, check out the HTTP Method Reference to understand request methods, the HTTP Status Codes reference for response codes, or the CORS Header Builder if you are configuring cross-origin headers alongside your protocol upgrade.
How to Use
- Review the comparison table which shows all features across HTTP/1.1, HTTP/2, and HTTP/3 by default.
- Click the protocol toggle buttons at the top to show or hide specific protocol versions (at least one must remain visible).
- Use the category filter buttons to narrow the table to a specific area such as Security, Performance, or Multiplexing.
- Read the color-coded cells: green means excellent support, yellow means adequate or partial, red means limited or not supported.
- Scroll down to the summary cards to see an at-a-glance score for each protocol.
- Expand the Migration Guide sections for step-by-step instructions on upgrading from HTTP/1.1 to HTTP/2 or from HTTP/2 to HTTP/3.
FAQ
What is the main difference between HTTP/2 and HTTP/3?
The most fundamental difference is the transport layer. HTTP/2 runs on TCP, while HTTP/3 runs on QUIC (which uses UDP). This means HTTP/3 eliminates TCP-level head-of-line blocking, supports connection migration when switching networks, and achieves faster connection establishment with 0-RTT resumption.
Should I upgrade directly from HTTP/1.1 to HTTP/3?
It is generally recommended to first adopt HTTP/2, then add HTTP/3. HTTP/2 is universally supported by modern browsers and servers, while HTTP/3 support is still growing. Most servers and CDNs that support HTTP/3 also support HTTP/2, so the browser can negotiate the best available protocol automatically.
Does HTTP/3 replace HTTP/2?
Not yet. HTTP/3 is designed to coexist with HTTP/2. Browsers will fall back to HTTP/2 (or even HTTP/1.1) if QUIC is blocked by a firewall or network middlebox. In practice, you should keep HTTP/2 enabled as a fallback even after deploying HTTP/3.
Why does HTTP/3 use UDP instead of TCP?
TCP's in-order delivery guarantee causes head-of-line blocking: if one packet is lost, all subsequent data must wait for the retransmission. QUIC uses UDP as the underlying transport and implements its own reliable delivery per stream, so a lost packet on one stream does not block other streams. QUIC also integrates TLS 1.3 directly, reducing handshake round trips.
What is head-of-line (HOL) blocking?
Head-of-line blocking occurs when a single slow or lost packet delays all other data behind it. In HTTP/1.1, this happens at both the HTTP and TCP layers. HTTP/2 solves it at the HTTP layer through multiplexing but is still vulnerable at the TCP layer. HTTP/3 eliminates HOL blocking entirely because QUIC streams are independent at the transport layer.
Is my data safe when using this tool?
Yes. This tool is a purely client-side reference that runs entirely in your browser. It does not send any data to external servers, does not use cookies, and does not collect analytics on your interactions. Everything is processed locally on your machine.
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