Cross-platform asynchronous I/O
C C++ Python Makefile M4 Shell Other
Latest commit c5bb773 Jan 21, 2017 @jBarz jBarz committed with bnoordhuis zos: use gyp OS label "os390" on z/OS
This is what `uname` on the system actually displays.
Also, other gyp based projects use 'os390'

PR-URL: #1207
Reviewed-By: Ben Noordhuis <>
Reviewed-By: Saúl Ibarra Corretgé <>
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docs doc: add repitition qualifier to version regexs Jan 20, 2017
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.gitignore gitignore: ignore VS temporary database files May 12, 2016
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LICENSE license: add license text we've been using for a while May 28, 2016 doc: add cjihrig alternative GPG ID Nov 15, 2016 zos: make platform functional Jan 18, 2017
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android-configure build: bump android ndk version Apr 26, 2016
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common.gypi zos: use gyp OS label "os390" on z/OS Jan 23, 2017 2017.01.10, Version 1.10.2 (Stable) Jan 9, 2017 build: python 2.x/3.x consistent print usage Feb 15, 2016
libuv.nsi build: add experimental Windows installer Jul 28, 2015 build: use '${prefix}' for pkg-config 'exec_prefix' Aug 19, 2016
uv.gyp zos: use gyp OS label "os390" on z/OS Jan 23, 2017
vcbuild.bat build,win: rename platform to msbuild_platform May 12, 2016



libuv is a multi-platform support library with a focus on asynchronous I/O. It was primarily developed for use by Node.js, but it's also used by Luvit, Julia, pyuv, and others.

Feature highlights

  • Full-featured event loop backed by epoll, kqueue, IOCP, event ports.

  • Asynchronous TCP and UDP sockets

  • Asynchronous DNS resolution

  • Asynchronous file and file system operations

  • File system events

  • ANSI escape code controlled TTY

  • IPC with socket sharing, using Unix domain sockets or named pipes (Windows)

  • Child processes

  • Thread pool

  • Signal handling

  • High resolution clock

  • Threading and synchronization primitives


Starting with version 1.0.0 libuv follows the semantic versioning scheme. The API change and backwards compatibility rules are those indicated by SemVer. libuv will keep a stable ABI across major releases.

The ABI/API changes can be tracked here.


libuv is licensed under the MIT license. Check the LICENSE file.



Official API documentation

Located in the docs/ subdirectory. It uses the Sphinx framework, which makes it possible to build the documentation in multiple formats.

Show different supported building options:

$ make help

Build documentation as HTML:

$ make html

Build documentation as HTML and live reload it when it changes (this requires sphinx-autobuild to be installed and is only supported on Unix):

$ make livehtml

Build documentation as man pages:

$ make man

Build documentation as ePub:

$ make epub

NOTE: Windows users need to use make.bat instead of plain 'make'.

Documentation can be browsed online here.

The tests and benchmarks also serve as API specification and usage examples.

Other resources

  • An Introduction to libuv — An overview of libuv with tutorials.
  • LXJS 2012 talk — High-level introductory talk about libuv.
  • libuv-dox — Documenting types and methods of libuv, mostly by reading uv.h.
  • learnuv — Learn uv for fun and profit, a self guided workshop to libuv.

These resources are not handled by libuv maintainers and might be out of date. Please verify it before opening new issues.


libuv can be downloaded either from the GitHub repository or from the downloads site.

Starting with libuv 1.7.0, binaries for Windows are also provided. This is to be considered EXPERIMENTAL.

Before verifying the git tags or signature files, importing the relevant keys is necessary. Key IDs are listed in the MAINTAINERS file, but are also available as git blob objects for easier use.

Importing a key the usual way:

$ gpg --keyserver \
  --recv-keys AE9BC059

Importing a key from a git blob object:

$ git show pubkey-saghul | gpg --import

Verifying releases

Git tags are signed with the developer's key, they can be verified as follows:

$ git verify-tag v1.6.1

Starting with libuv 1.7.0, the tarballs stored in the downloads site are signed and an accompanying signature file sit alongside each. Once both the release tarball and the signature file are downloaded, the file can be verified as follows:

$ gpg --verify libuv-1.7.0.tar.gz.sign

Build Instructions

For GCC there are two build methods: via autotools or via GYP. GYP is a meta-build system which can generate MSVS, Makefile, and XCode backends. It is best used for integration into other projects.

To build with autotools:

$ sh
$ ./configure
$ make
$ make check
$ make install


First, Python 2.6 or 2.7 must be installed as it is required by GYP. If python is not in your path, set the environment variable PYTHON to its location. For example: set PYTHON=C:\Python27\python.exe

To build with Visual Studio, launch a git shell (e.g. Cmd or PowerShell) and run vcbuild.bat which will checkout the GYP code into build/gyp and generate uv.sln as well as related project files.

To have GYP generate build script for another system, checkout GYP into the project tree manually:

$ git clone build/gyp


For Debug builds (recommended) run:

$ ./ -f make
$ make -C out

For Release builds run:

$ ./ -f make
$ BUILDTYPE=Release make -C out

Run ./ -f make -Dtarget_arch=x32 to build x32 binaries.



$ ./ -f xcode
$ xcodebuild -ARCHS="x86_64" -project uv.xcodeproj \
     -configuration Release -target All

Using Homebrew:

$ brew install --HEAD libuv

Note to OS X users:

Make sure that you specify the architecture you wish to build for in the "ARCHS" flag. You can specify more than one by delimiting with a space (e.g. "x86_64 i386").



$ source ./android-configure NDK_PATH gyp
$ make -C out

Note for UNIX users: compile your project with -D_LARGEFILE_SOURCE and -D_FILE_OFFSET_BITS=64. GYP builds take care of that automatically.

Using Ninja

To use ninja for build on ninja supported platforms, run:

$ ./ -f ninja
$ ninja -C out/Debug     #for debug build OR
$ ninja -C out/Release

Running tests


$ ./ -f make
$ make -C out
$ ./out/Debug/run-tests

Supported Platforms


AIX Notes

AIX support for filesystem events requires the non-default IBM bos.ahafs package to be installed. This package provides the AIX Event Infrastructure that is detected by autoconf. IBM documentation describes the package in more detail.

AIX support for filesystem events is not compiled when building with gyp.


See the guidelines for contributing.