Does HTTP/2 replace HTTP/1.1?

HTTP/2 is the successor but both coexist. Web servers negotiate the protocol via ALPN. Modern browsers and servers use HTTP/2 automatically when available. HTTP/1.1 remains as fallback.

HTTP/1.1 vs HTTP/2

Differences, use cases, and when to use each

HTTP/1.1 is the long-standing web protocol using sequential request-response over separate connections. HTTP/2 introduces multiplexing, header compression, and server push, dramatically improving performance for modern web pages with many assets.

Quick Comparison

Feature	HTTP/1.1	HTTP/2
Multiplexing	No (one request per connection)	Yes (many requests per connection)
Header Compression	No (text headers repeated)	Yes (HPACK compression)
Server Push	Not supported	Supported (send assets before requested)
TLS Requirement	Optional	Required in practice (browsers enforce)
Performance on Many Assets	Slow (connection limits)	Fast (multiplexed)

When to Use Each

When to Use HTTP/1.1

HTTP/1.1 is a fallback only — for very old clients, internal tools, or simple single-request APIs where HTTP/2's features aren't needed.

When to Use HTTP/2

Use HTTP/2 for all public web servers. It's supported by 96%+ of browsers, required for HTTPS, and provides dramatically better performance for modern multi-asset web pages.

Pros & Cons

HTTP/1.1

No TLS requirement for simple use

Universally supported (even IE)

Head-of-line blocking

One request per connection (slow for many assets)

HTTP/2

Multiplexed requests

Header compression

Much faster for multi-asset pages

Requires HTTPS in browser context

More complex server setup

Verdict

HTTP/2 for all production web servers. The performance gains (multiplexing, HPACK) are significant for modern web pages. HTTP/3 (QUIC) is the next evolution, also worth enabling.

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