butterfly/kb
1
0
Fork 0
Code Issues Pull Requests Actions Packages Projects Releases Wiki Activity
9d19eebc64
kb/data/developer.mozilla.org/en-US/docs/Glossary/ALPN-0.md

10 KiB
Raw Blame History

title chunk source category tags date_saved instance
ALPN - Glossary | MDN 1/3 https://developer.mozilla.org/en-US/docs/Glossary/ALPN reference web, html, css, javascript, documentation 2026-05-05T05:23:31.389465+00:00 kb-cron

MDN HTML HTML: Markup language

HTML reference

HTML guides

Markup languages

CSS CSS: Styling language

CSS reference

CSS guides

Layout cookbook

JavaScriptJS JavaScript: Scripting language

JS reference

JS guides

Web APIs Web APIs: Programming interfaces

Web API reference

Web API guides

All All web technology

Technologies

Topics

Learn Learn web development

Frontend developer course

Learn HTML

Learn CSS

Learn JavaScript

Tools Discover our tools

About Get to know MDN better

Blog

  1. Glossary
  2. ALPN

ALPN

Application-Layer Protocol Negotiation (ALPN) is a TLS extension (defined in RFC 7301) for identifying what application-layer protocol is negotiating the encrypted connection, without requiring additional round trips to do so.

Protocol Identification sequence
HTTP/1.1 0x68 0x74 0x74 0x70 0x2F 0x31 0x2E 0x31 ("http/1.1")
HTTP/2 0x68 0x32 ("h2")
HTTP/2 over cleartext TCP 0x68 0x32 0x63 ("h2c")
HTTP/3 0x68 0x33 ("h3")

In this article

See also