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Duktape - embeddable Javascript engine with a focus on portability and compact footprint

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:warning: Master branch is undergoing incompatible changes for Duktape 3.x. To track Duktape 2.x, follow the



Duktape is an embeddable Javascript engine, with a focus on portability and compact footprint.

Duktape is easy to integrate into a C/C++ project: add

, and
to your build, and use the Duktape API to call ECMAScript functions from C code and vice versa.

Main features:

  • Embeddable, portable, compact
  • ECMAScript E5/E5.1 compliant, with some semantics updated from ES2015+
  • Partial support for ECMAScript 2015 (E6) and ECMAScript 2016 (E7), Post-ES5 feature status, kangax/compat-table
  • ES2015 TypedArray and Node.js Buffer bindings
  • WHATWG Encoding API living standard
  • Built-in debugger
  • Built-in regular expression engine
  • Built-in Unicode support
  • Minimal platform dependencies
  • Combined reference counting and mark-and-sweep garbage collection with finalization
  • Custom features like coroutines
  • Property virtualization using a subset of ECMAScript ES2015 Proxy object
  • Bytecode dump/load for caching compiled functions
  • Distributable includes an optional logging framework, CommonJS-based module loading implementations, CBOR bindings, etc
  • Liberal MIT license (see LICENSE.txt)

See for packaged end-user downloads and documentation. The end user downloads are also available from the duktape-releases repo as both binaries and in unpacked form as git tags.

Have fun!


About this repository

This repository is intended for Duktape developers only, and contains Duktape internals: test cases, internal documentation, sources for the web site, etc.

Getting started: end user

When embedding Duktape in your application you should use the packaged source distributables available from See for the basics.

The distributable

directory contains a
configuration header and amalgamated sources for Duktape default configuration. If necessary, use
python tools/
to create header and sources for customized configuration options, see For example, to enable fastint support (example for Linux):
$ tar xvfJ duktape-2.0.0.tar.xz
$ cd duktape-2.0.0
$ rm -rf src-custom
$ python tools/ \
      --source-directory src-input \
      --output-directory src-custom \
      --config-metadata config \

src-custom/ will now contain: duktape.c, duktape.h, duk_config.h.

You can download and install Duktape using the vcpkg dependency manager:

$ git clone
$ cd vcpkg
$ ./
$ ./vcpkg integrate install
$ vcpkg install duktape

The Duktape port in vcpkg is kept up to date by Microsoft team members and community contributors. If the version is out of date, please create an issue or pull request on the vcpkg repository.

You can also clone this repository, make modifications, and build a source distributable on Linux, macOS, and Windows using

python util/
. You'll need Python 2 and Python YAML binding.

Getting started: modifying and rebuilding the distributable

If you intend to change Duktape internals and want to rebuild the source distributable in Linux, macOS, or Windows:

# Linux; can often install from packages or using 'pip'
# Install Node.js >= 14.x
$ sudo apt-get install python python-yaml
$ python util/


Install Python 2.7.x

Install Node.js >= 14.x

$ pip install PyYAML $ python util/


; Install Python 2.7.x from, and add it to PATH ; Install Node.js >= 14.x > pip install PyYAML > python util\

The source distributable directory will be in


For platform specific notes see

Getting started: other development (Linux only)

Other development stuff, such as building the website and running test cases, is based on a

supported for Linux x86-64 only.

There are some Docker images which can simplify the development setup and also document the needed packages. These are also supported for Linux x86-64 only. For example:

# Build Docker images.  This takes a long time.
$ make docker-images

Equivalent of 'make dist-source', but runs inside a container.

$ make docker-dist-source-wd

Run a shell with /work/duktape containing a disposable master snapshot.

$ make docker-shell-master

Run a shell with /work/duktape mounted from current directory.

This allows editing, building, testing, etc with an interactive

shell running in the container.

$ make docker-shell-wdmount

For non-native images you may need:

There is limited support for developing on macOS via Docker. On Apple M1:

$ make docker-images-arm64
$ DOCKER_ARCH=arm64 make docker-shell-wdmount

Branch policy

  • The

    branch is used for active development. Even though pull requests are tested before merging, master may still be broken from time to time. When development on a new major release starts, master will also get API incompatible changes without warning. For these reasons you should generally not depend on the master branch for building your project; use a release tag (e.g.
    ) or a release maintenance branch (e.g.
    ) instead.
  • Pull requests and their related branches are frequently rebased so you should not fork off them. Pull requests may be open for a while for testing and discussion.

  • Release tags like

    are used for releases and match the released distributables. These are stable once the release is complete.
  • Maintenance branches are used for backporting fixes and features for maintenance releases. Documentation changes go to master for maintenance releases too. For example,

    was created for the 1.5.0 release and is used for 1.5.x maintenance releases.
  • A maintenance branch is also created for a major release when master moves on to active development of the next major release. For example,

    was created when 1.5.0 was released (last planned 1.x release) and development of 2.0.0 (with API incompatible changes) started on master. The 1.6.0 and 1.7.0 releases were made from
    for example.


Duktape uses Semantic Versioning for official releases. Builds from Duktape repo are not official releases and don't follow strict semver, mainly because

needs to have some compromise value that won't be strictly semver conforming. Because Duktape tracks the latest ECMAScript specification versions, compliance fixes are made in minor versions even when they are technically not backwards compatible. See Versioning for details.

Reporting bugs


Security critical GitHub issues (for example anything leading to a segfault) are tagged




Copyright and license

See AUTHORS.rst and LICENSE.txt.

Duktape Wiki is part of Duktape documentation and under the same copyright and license.

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