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CDT (Contract Development Toolkit)

Contract Development Toolkit (CDT) is a C/C++ toolchain targeting WebAssembly (WASM) and a set of tools to facilitate development of smart contracts written in C/C++ that are meant to be deployed to an Antelope blockchain.

In addition to being a general purpose WebAssembly toolchain, specific features and optimizations are available to support building Antelope-based smart contracts. This new toolchain is built around Clang 9, which means that CDT inherits the optimizations and analyses from that version of LLVM, but as the WASM target is still considered experimental, some optimizations are incomplete or not available.

Repo organization

The main branch is the development branch: do not use this for production. Refer to the release page for current information on releases, pre-releases, and obsolete releases as well as the corresponding tags for those releases.

Binary packages

CDT currently supports Linux x86_64 Debian packages. Visit the release page to download the package for the appropriate version of CDT. This is the fastest way to get started with the software.

Debian package install

The latest version of CDT is 3.0. Download the appropriate version of the Debian package and then install as follows:

sudo apt install ./cdt_3.1.0-rc1_amd64.deb

Debian package uninstall

To remove CDT that was installed using a Debian package, simply execute the following command:

sudo apt remove cdt

Building from source

Recent Ubuntu LTS releases are the only Linux distributions that we fully support. Other Linux distros and other POSIX operating systems (such as macOS) are tended to on a best-effort basis and may not be full featured.

The instructions below assume that you are building on Ubuntu 20.04.

Install dependencies

apt-get update && apt-get install   \
        build-essential             \
        clang                       \
        cmake                       \
        git                         \
        libxml2-dev                 \
        opam ocaml-interp           \
        python3                     \
        python3-pip                 \
python3 -m pip install pygments

Allowing integration tests to build

Integration tests require access to a build of Leap, a C++ implementation of the Antelope protocol. Simply installing Leap from a binary package will not be sufficient.

If you do not wish to build Leap, you can continue with building CDT but without building the integration tests. Otherwise, follow the instructions below before running cmake.

First, ensure that Leap has been built from source (see Leap's README for details) and identify the build path, e.g. /path/to/leap/build/.

Then, execute the following command in the same terminal session that you will use to build CDT:

export leap_DIR=/path/to/leap/build/lib/cmake/leap

Now you can continue with the steps to build CDT as described. When you run cmake make sure that it does not report leap package not found. If it does, this means CDT was not able to find a build of Leap at the specified path in leap_DIR and will therefore continue without building the integration tests.


If issues persist with ccache when building CDT, you can disable ccache:


Build CDT

A Warning On Parallel Compilation Jobs (-j flag): When building C/C++ software often the build is performed in parallel via a command such as make -j $(nproc) which uses the number of CPU cores as the number of compilation jobs to perform simultaneously. However, be aware that some compilation units (.cpp files) in CDT are extremely complex and can consume a large amount of memory to compile. If you are running into issues due to amount of memory available on your build host, you may need to reduce the level of parallelization used for the build. For example, instead of make -j $(nproc) you can try make -j2. Failures due to memory exhaustion will typically but not always manifest as compiler crashes.

git clone --recursive
cd cdt
mkdir build
cd build
cmake ..
make -j $(nproc)

The binaries will be located at in the build/bin directory. You can export the path to the directory to your PATH environment variable which allows you to conveniently use them to compile contracts without installing CDT globally. Alternatively, you can use CMake toolchain file located in build/lib/cmake/CDTWasmToolchain.cmake to compile the contracts in your CMake project, which also allows you to avoid installing CDT globally.

If you would prefer to install CDT globally, see the section Install CDT below.

Build CDT in debug mode

To build CDT in debug mode (with debug symbols) you need to add the following flags to cmake command:


Run tests

Run unit tests

cd build


Run integration tests (if built)

cd build/tests/integration


Install CDT

Installing CDT globally on your system will install the following tools in a location accessible to your PATH:

  • cdt-abidiff
  • cdt-ar
  • cdt-cc
  • cdt-cpp
  • cdt-init
  • cdt-ld
  • cdt-nm
  • cdt-objcopy
  • cdt-objdump
  • cdt-ranlib
  • cdt-readelf
  • cdt-strip
  • eosio-pp
  • eosio-wasm2wast
  • eosio-wast2wasm

It will also install CMake files for CDT accessible within a cmake/cdt directory located within your system's lib directory.

Manual installation

One option for installing CDT globally is via make install. From within the build directory, run the following command:

sudo make install

Package installation

A better option for installing CDT globally is to generate a package and then install the package. This makes uninstalling CDT much easier.

From within the build directory, run the following commands to generate a Debian package:

cd packages
bash ./ deb ubuntu-20.04 amd64
sudo apt install ./cdt_*_amd64.deb

Uninstall CDT

Uninstall CDT after manual installation with make

sudo rm -fr /usr/local/cdt
sudo rm -fr /usr/local/lib/cmake/cdt
sudo rm /usr/local/bin/eosio-*
sudo rm /usr/local/bin/cdt-*

Uninstall CDT that was installed using a Debian package

sudo apt remove cdt