LiteSpeed QUIC (LSQUIC) Library is an open-source implementation of QUIC and HTTP/3 functionality for servers and clients. Most of the code in this distribution is used in our own products: LiteSpeed Web Server, LiteSpeed ADC, and OpenLiteSpeed.

QUIC versions v1, v2, and Internet-Draft version 29 are enabled by default. Deprecated versions ID-27 and the older "Google" QUIC versions Q043, Q046, and Q050 are still supported, but are not enabled by default.

LiteSpeed QUIC is mostly compliant to the follow RFCs:

• RFC 9000 QUIC: A UDP-Based Multiplexed and Secure Transport
• RFC 9001 Using TLS to Secure QUIC
• RFC 9002 QUIC Loss Detection and Congestion Control
• RFC 9114 HTTP/3
• RFC 9204 QPACK: Field Compression for HTTP/3

The following QUIC protocol extensions are implemented:

• RFC 9368 Compatible Version Negotiation for QUIC
• RFC 9369 QUIC Version 2
• RFC 9218 Extensible Prioritization Scheme for HTTP
• RFC 9221 An Unreliable Datagram Extension to QUIC
• RFC 9287 Greasing the QUIC Bit
• ACK Frequency
• WebTransport

Documentation is available at https://lsquic.readthedocs.io/en/latest/.

In addition, see example programs for API usage and EXAMPLES.txt for some compilation and run-time options.

To build LSQUIC, you need CMake, zlib, and BoringSSL. The example program uses libevent to provide the event loop.

BoringSSL is not packaged; you have to build it yourself. The process is straightforward. You will need go installed.

1. Clone BoringSSL by issuing the following command:

git clone https://boringssl.googlesource.com/boringssl
cd boringssl

You may need to install pre-requisites like zlib and libevent.

2. Use specific BoringSSL version

git checkout 0.20250807.0

Or, just try the latest master branch.

3. Compile the library

cmake . &&  make

Remember where BoringSSL sources are:

BORINGSSL=$PWD

If you want to turn on optimizations, do

cmake -DCMAKE_BUILD_TYPE=Release . && make

If you want to build as a library, (necessary to build lsquic itself as as shared library) do:

cmake -DBUILD_SHARED_LIBS=1 . && make

LSQUIC's http_client, http_server, and the tests link BoringSSL libraries statically. Following previous section, you can build LSQUIC as follows:

1. Get the source code

git clone https://github.com/litespeedtech/lsquic.git
cd lsquic
git submodule update --init

2. Compile the library

Statically:

# $BORINGSSL is the top-level BoringSSL directory from the previous step
cmake -DLIBSSL_DIR=$BORINGSSL .
make

As a dynamic library:

cmake -DLSQUIC_SHARED_LIB=1 -DLIBSSL_DIR=$BORINGSSL .
make

3. Run tests

make test

The library and the example client and server can be built with Docker.

Initialize Git submodules:

cd lsquic
git submodule update --init

Build the Docker image:

docker build -t lsquic .

Then you can use the examples from the command line. For example:

sudo docker run -it --rm lsquic http_client -s www.google.com  -p / -o version=h3
sudo docker run -p 12345:12345/udp -v /path/to/certs:/mnt/certs -it --rm lsquic http_server -c www.example.com,/mnt/certs/chain,/mnt/certs/key

The library has been tested on the following platforms:

• Linux
  • i386
  • x86_64
  • ARM (Raspberry Pi 3)
• FreeBSD
  • i386
• MacOS
  • x86_64
• iOS
  • ARM
• Android
  • ARM
• Windows
  • x86_64

Do not hesitate to report bugs back to us. Even better, send us fixes and improvements!

Have fun,

LiteSpeed QUIC Team.

Copyright (c) 2017 - 2026 LiteSpeed Technologies Inc