Python
- Qiskit Terra - Python library for quantum circuit rewriting and optimization (supported by IBM).
- PyZX - Python library for quantum circuit rewriting and optimisation using the ZX-calculus.
- QGL2 Compiler - Language compiler for imperative Quantum Gate Language (QGL).
- Qubiter - Quantum compiler with Python wrapper for LAPACK's CS Decomposition to build a binary tree of matrices.
C++
- ScaffCC - Compilation, analysis and optimization framework for the Scaffold quantum programming language.
Julia
Mathematica
- UniversalQCompiler - Synthesis of isometries (including unitaries and state preparation), channels and POVMs.
Common Lisp
- quilc - Rigetti's optimizing Quil compiler.