Minimal implementation of the QUIC protocol
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Latest commit 3bab704 Nov 8, 2018


Minimalist implementation of the QUIC protocol, as defined by the IETF. The IETF spec started with the version of QUIC defined by Google and implemented in Chrome, but the IETF spec is independent of Chrome, and does not attempt to be backward compatible. The main developer is Christian Huitema.

The first goal of this project is to provide feedback on the development of a QUIC standard in the IETF QUIC WG. Information on the WG is available at The in-progress version of the spec is available on GitHub at

The second goal is to experiment with API for non-HTTP development, such as DNS over QUIC. Then there are plenty of other features we may dream off, such as support for multipath, or support for peer-to-peer applications. That's on the horizon, but not there now.

The code in this repo is a work in progress. In fact, the specification itself is a work in progress. The working group is progressing by running a series of meetings and of interop trials between several implementations, listed at The current interoperability matrix is listed at

Bastian Köcher has developed bindings of the picoquic library to RUST ( His repository can be found here: You may want to check it.


Picoquic is currently developed as a Visual Studio 2017 project, and simultaneously tested on Windows and on Linux. It has a dependency on the Picotls implementation of TLS 1.3 ( Picotls has two mode, a feature rich version that depends on OpenSSL, and a leaner version that only depends on the "minicrypto" library. For now, Picoquic uses the OpenSSL version, and has a dependency on OpenSSL.

The project consists of a core library (picoquic), of a test library (picoquictest), and of a test program (picoquicfirst). All these are written in C. In the Visual Studio project, the test library is wrapped up in the Visual Studio unittest framework, which makes for convenient regression testing during development. In the Linux builds, the tests are run through a command line program.


As explained in the Wiki, Picoquic is actively tested against other implementations during the QUIC Interop days. See

The current version is aligned with draft 15. Most big features are now tested, including the revised interface between QUIC and TLS, but we still have to fully develop and test key rollover.

In parallel, we still plan to do an implementation of DNS over QUIC (

We are spending time bettering the implementation. Until now the focus has been on correctness rather than performance. We will keep correctness, but we will improve performance, especially in light of practical experience with applications. Suggestions are wellcome.

Building Picoquic

Picoquic is developed in C, and can be built under Windows or Linux. Building the project requires first managing the dependencies, Picotls ( and OpenSSL. Please note that you will need a recent version of Picotls -- the TLS API depends on commits from Aug 14, 2018, and the support for the EOED removal extension of TLS 1.3 depends on commits from Oct 4, 2018.

Picoquic on Windows

To build Picoquic on Windows, you need to:

  • Install and build Openssl on your machine

  • Document the location of the Openssl install in the environment variable OPENSSLDIR (OPENSSL64DIR for the x64 builds)

  • Clone and compile Picotls, using the Picotls for Windows options

  • Clone and compile Picoquic, using the Visual Studio 2017 solution picoquic.sln included in the sources.

  • You can use the unit tests included in the Visual Studio solution to verify the port.

Picoquic on Linux

The build experience on Linux is now much improved, thanks to check-ins from Deb Banerjee and Igor Lubashev.

To build Picoquic on Linux, you need to:

  • Install and build Openssl on your machine

  • Clone and compile Picotls, using cmake as explained in the Picotls documentation.

  • Clone and compile Picoquic:

   cmake .
  • Run the test program "picoquic_ct" to verify the port.

Picoquic on MacOSX

Thanks to Frederik Deweerdt for ensuring that Picoquic runs on MacOSX. The build steps are the same as for Linux.

Picoquic on FreeBSD

Same build steps as Linux. Picoquic probably also works on other BSD variants, but only FreeBSD has been tested so far.

Developing applications

Sorry, not all that much documentation yet. This will come as we populate the wiki. Your best bet is to look at the demonstration program "picoquicdemo" that is included in the release. The sources are in "picoquicfirst/picoquicdemo.c".

Testing previous versions

The code is constantly updated to track the latest version of the specification. When we can, we maintain compatibility with previous drafts, so as to facilitate interop testing with other implementations. But some version changes will change the wire format or the encryption code in incompatible ways. That's the reason why we only support draft-15 at this stage, although both the client and server can be launched in draft-14 compatibility mode, using the option "-v FF00000E".