BehaviorTree.CPP 4.9

This C++ 17 library provides a framework to create BehaviorTrees. It was designed to be flexible, easy to use, reactive and fast.

Even if our main use-case is robotics, you can use this library to build AI for games, or to replace Finite State Machines.

There are a few features that make BehaviorTree.CPP unique, when compared to other implementations:

• It makes asynchronous Actions, i.e. non-blocking, a first-class citizen.

• You can build reactive behaviors that execute multiple Actions concurrently (orthogonality).

• Trees are defined using a Domain Specific scripting language (based on XML), and can be loaded at run-time; in other words, even if written in C++, the morphology of the Trees is not hard-coded.

• You can statically link your custom TreeNodes or convert them into plugins and load them at run-time.

• It provides a type-safe and flexible mechanism to do Dataflow between Nodes of the Tree.

• It includes a logging/profiling infrastructure that allows the user to visualize, record, replay, and analyze state transitions.

Documentation

• Tutorials and general documentation: https://www.behaviortree.dev/
• Auto-generated Doxygen: https://behaviortree.github.io/BehaviorTree.CPP/
• Community support and forum: https://github.com/BehaviorTree/BehaviorTree.CPP/discussions

GUI Editor

Editing a BehaviorTree is as simple as editing an XML file in your favorite text editor.

If you are looking for a fancier graphical user interface (and I know you do) check Groot2 out.

How to compile

BT.CPP requires a compiler that supports C++17.

Three build systems are supported:

• colcon (ament), if you use ROS2
• conan otherwise (Linux/Windows).
• straight cmake if you want to be personally responsible for dependencies :)

Compiling with conan:

[!NOTE] Conan builds require CMake 3.23 or newer.

Assuming that you are in the root directory of BehaviorTree.CPP:

conan install . -s build_type=Release --build=missing
cmake --preset conan-release
cmake --build --preset conan-release

If you have dependencies such as ZeroMQ and SQlite already installed and you don’t want to use conan, simply type:

mkdir build_release
cmake -S . -B build_release
cmake --build build_release --parallel

BT.CPP includes its own copy of nlohmann/json. To use the one installed in your system instead (version 3.10 or newer), add -DUSE_VENDORED_JSON=OFF. Since nlohmann::json is part of the public API, everything that links BT.CPP must then be compiled with that same version.

If you want to build in a pixi project (conda virtual environment).

pixi run build

If you want to use BT.CPP in your application, please refer to the example here: https://github.com/BehaviorTree/btcpp_sample .

Installing BehaviorTree.CPP (vcpkg)

Alternatively, you can build and install behaviortree-cpp using vcpkg dependency manager:

git clone https://github.com/Microsoft/vcpkg.git
cd vcpkg

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Changelog for package behaviortree_cpp

4.10.0 (2026-07-24)

• reject trailing characters in SwitchNode numeric comparison (#1178)

• Pin ament install destinations to lib/include/bin (fixes #1175) (#1176) The ROS build farm (bloom/debhelper) configures with -DCMAKE_INSTALL_LIBDIR=lib/<multiarch-triplet>. Since #1152 made the BTCPP_*_DESTINATION variables honor GNUInstallDirs, farm binaries installed libbehaviortree_cpp.so to /opt/ros/<distro>/lib/x86_64-linux-gnu, which breaks ament_export_libraries lookup in downstream packages and is not on the LD_LIBRARY_PATH set by the ament environment hooks. Shadow the cache variables with plain set() in the ament build path, so ROS builds always install to $prefix/lib regardless of CMAKE_INSTALL_LIBDIR, while standalone builds keep the GNUInstallDirs override behavior introduced for #1120. Also add a ros2-lyrical CI job that emulates the build farm flags and asserts the library lands in $prefix/lib. Co-authored-by: Claude Fable 5 <<noreply@anthropic.com>>

• fix out-of-bounds read in Groot2 hook insert handler (#1170)

  • fix out-of-bounds read in Groot2 hook insert handler
  • exclude Parallel.FailingParallel from macOS CI test run

• Add scripted return status support for TestNode mocks (#1169) Introduce [return_status_script]{.title-ref} on TestNodeConfig, allowing a mock's completion status to be computed at runtime from blackboard state instead of being fixed. When set, it takes precedence over [return_status]{.title-ref}; it may reference the NodeStatus names (SUCCESS/FAILURE/...) and is rejected if it resolves to IDLE. The NodeStatus enum names are injected only into the return_status_script environment. The pre-existing success_script/failure_script/post_script continue to evaluate against the node's own enums, so a blackboard entry named like a status (e.g. "SUCCESS") is not shadowed. To pay the ABI break only once, TestNode's state is moved behind a PImpl, so future changes to it no longer alter the layout consumers link against (mirroring StatusChangeLogger). The new return_status_script field is appended at the end of TestNodeConfig, preserving the byte offsets of the existing fields. Also add JSON validation rejecting a TestNodeConfig with neither a return_status nor a return_status_script, and a tutorial example (t15_nodes_mocking_strict_failure) demonstrating the strict-failure flow. Addresses #995. Co-authored-by: Pepe <<pepe@ross-robotics.co.uk>> Co-authored-by: Claude Opus 4.8 <<noreply@anthropic.com>>

• Fix ROOT blackboard export in Groot2 publisher (#1132) (#1168) When a subtree's blackboard is backed by a separate root blackboard (e.g. created via [Blackboard::create(external_root)]{.title-ref} to expose [@]{.title-ref} globals), the Groot2 publisher never exported those root entries, so they were invisible in Groot2. Export the root blackboard under the reserved name [ROOT]{.title-ref} whenever a requested subtree resolves to a distinct root blackboard.

  - Deduplicate the [ROOT]{.title-ref} payload when several subtrees share the same root blackboard.

  - Return the dump as [Expected<>]{.title-ref} and send an error reply for ambiguous requests: a subtree literally named [ROOT]{.title-ref}, or a request spanning multiple distinct root blackboards.

  - Add functional coverage to gtest_groot2_publisher_integration.cpp using the shared Groot2Test helpers (makePublisher/Client).

  - Enable [/utf-8]{.title-ref} for behaviortree_cpp_test on MSVC so the Unicode name-validation tests build on Windows. Closes #1130 Co-authored-by: magic-alt <<zaqwerss@outlook.com>> Co-authored-by: Claude Opus 4.8 <<noreply@anthropic.com>>

• Add macOS CI and fix Apple libc++ build (#1167)

  * Add macOS build to CI Add a Conan + CMake workflow running on macos-latest (Apple Silicon, AppleClang + libc++). This exercises the Apple standard-library toolchain that other CI jobs (Ubuntu/GCC, Windows/MSVC, conda/Clang) do not, catching Apple-specific breakage such as the missing floating-point std::from_chars. The job mirrors the existing cmake_ubuntu.yml Conan flow (conan install -> cmake --preset conan-release -> ctest), pinning compiler.cppstd=17 as the Windows job does. Co-Authored-By: Claude Opus 4.8 <<noreply@anthropic.com>>

  * Fix Apple libc++ build: guard floating-point std::from_chars Apple's libc++ deletes the floating-point std::from_chars overload (and undefines __cpp_lib_to_chars), so the unguarded double parse

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