This book effort was started in March 2018. The plan is to document HTTP/3 and its underlying protocol: QUIC. Why, how they work, protocol details, the implementations and more.

The book is entirely free and is meant to be a collaborative effort involving anyone and everyone who wants to help out.


A reader of this book is presumed to have a basic understanding of TCP/IP networking, the fundamentals of HTTP and the web. For further insights and specifics about HTTP/2 we recommend first reading up the details in http2 explained.


This book is created and the work is started by Daniel Stenberg. Daniel is the founder and lead developer of curl, the world's most widely used HTTP client software. Daniel has worked with and on HTTP and internet protocols for over two decades and is the author of http2 explained.


The home page for this book is found at daniel.haxx.se/http3-explained.

Help out

If you find mistakes, omissions, errors or blatant lies in this document, please send us a refreshed version of the affected paragraph and we will make amended versions. We will give proper credits to everyone who helps out. I hope to make this document better over time.

Preferably, you submit errors or pull requests on the book's GitHub page.


This document and all its contents are licensed under the Creative Commons Attribution 4.0 license.

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