cmake   
[ Highway ](https://github.com/google/highway) |  Provides performance-portable, length-agnostic SIMD/vector intrinsics. Supports: SSE3, SSE4, AVX*, NEON, SVE*, WASM SIMD, RISC-V, POWER. ( [ Doc ](https://github.com/google/highway/tree/master/g3doc) )  |  [ Apache-2.0 ](https://github.com/google/highway/blob/master/LICENSE) |  cmake   
[ HPX ](https://github.com/STEllAR-GROUP/hpx/) |  A general purpose C++ runtime system for parallel and distributed applications of any scale ( [ Doc ](https://hpx.stellar-group.org/about/) )  |  BSL-1.0  |  cmake, vcpkg   
[ Intel TBB ](https://software.intel.com/content/www/us/en/develop/tools/threading-building-blocks.html) |  Intel® TBB is a cross-platform C++ library for shared memory parallel programming and heterogeneous computing. The library provides: generic parallel algorithms, concurrent containers, a scalable memory allocator, work-stealing task scheduler, and low-level synchronization primitives. ( [ Src ](https://github.com/oneapi-src/oneTBB) ) ( [ Doc ](https://software.intel.com/content/www/us/en/develop/tools/threading-building-blocks/documentation.html) )  |  [ Apache-2.0 ](https://github.com/oneapi-src/oneTBB/blob/tbb_2020/LICENSE) or Commercial  |  cmake, make   
[ KOKKOS ](https://github.com/kokkos/kokkos) |  A programming model for writing performance portable HPC applications, using CUDA, HIP, SYCL, HPX, OpenMP and C++ threads as backends ( [ Doc ](https://kokkos.github.io/kokkos-core-wiki/programmingguide.html) )  |  [ Custom ](https://github.com/kokkos/kokkos#License-1-ov-file) |  cmake, make   
[ libopenmpi ](https://www.open-mpi.org/) |  The Open MPI Project is an open-source Message Passing Interface implementation  |  [ 3-clause BSD ](https://www.open-mpi.org/community/license.php) |   
[ libsimdpp ](https://github.com/p12tic/libsimdpp) |  A portable zero-overhead C++ low level SIMD library.  |  Boost  |  header-only; cmake   
[ MPL ](https://github.com/rabauke/mpl) |  A C++-17-friendly interface to the standard [ Message Passing Interface ](https://www.mpi-forum.org/) |  BSD 3-Clause "New" or "Revised"  |  header-only; cmake   
[ MutexGear ](https://github.com/oleh-derevenko/mutexgear) |  A mutex-only synchronization (wheel, rwlock, work queues) C/C++11 library  |  [ The MutexGear Library ](https://github.com/oleh-derevenko/mutexgear/blob/master/License-MutexGear.txt) |  configure, msvc, make   
[ OpenMP ](https://www.openmp.org/specifications/) |  The OpenMP API specification for parallel programming  |  |   
[ PoCL ](http://portablecl.org/index.html) |  A portable retargetable open-source (LLVM based) implementation of the OpenCL standard. ( [ Src ](https://github.com/pocl/pocl) ) ( [ Doc ](http://portablecl.org/docs/html) )  |  MIT  |  cmake   
[ RaftLib ](https://raftlib.io) |  A C++17 stream-like concurrent actors that enable parallel data-flow computations  |  Apache-2.0  |  cmake   
[ SObjectizer ](https://github.com/Stiffstream/sobjectizer) |  A small cross-platform framework for concurrent and event-driven applications in C++ by using actor and publish-subscribe models.  |  BSD-3-Clause  |  cmake, vcpkg, conan   
[ stdgpu ](https://github.com/stotko/stdgpu) |  Efficient STL-like Data Structures on the GPU  |  Apache 2.0  |  cmake   
[ subprocess ](https://github.com/benman64/subprocess) |  C++17/20 cross-platform library for running subprocesses  |  MIT  |  cmake, teaport   
[ Taskflow ](https://github.com/taskflow/taskflow) |  Parallel Task Programming in Modern C++  |  [ TASKFLOW MIT ](https://github.com/taskflow/taskflow/blob/master/LICENSE) |  cmake   
[ task-thread-pool ](https://github.com/alugowski/task-thread-pool) |  Fast and lightweight thread pool for C++11 and newer.  |  BSD-2-Clause or MIT or BSL-1.0  |  cmake, vcpkg, single header   
[ ThreadPool ](https://github.com/hosseinmoein/Leopard) |  A simple light-weight thread pool  |  BSD-3-Clause  |  header-only; cmake, make   
[ thread_pool ](https://github.com/DeveloperPaul123/thread-po