Cython
Cython is a free static compiler for Python and the extended Cython language, used to create C extensions for Python.
What Cython is
Cython is a free static compiler for Python and the extended Cython language, used to create C extensions for Python. It translates source into C or C++ that can be compiled as Python extension modules. Optional static type declarations can help generate more efficient C code, while declared C and C++ types let Python code call existing C or C++ code. Cython also supports source-level debugging across Python, Cython, and C. The project describes uses such as wrapping external C libraries, embedding CPython in applications, and speeding up Python code with fast C modules. It can be used with multidimensional NumPy arrays and integrated with low-level libraries and applications. Installation is available through pip, and some scientific Python distributions, including Anaconda and Sage, bundle it. A C compiler is required; the installation guide covers Linux, macOS, and Windows. The homepage describes generated-code compatibility with major C and C++ compilers for CPython 3.8 and later, and calls PyPy support mostly usable. Limited API and free-threading support in Cython 3.1 are marked experimental.
Good
- Generates C or C++ extension-module source.
- Optional types can improve generated C code.
- Supports debugging across Python, Cython, and C.
- Works with multidimensional NumPy arrays.
- Free under the Apache 2.0 License.
Watch out
- A C compiler is required.
- Limited API and free-threading support are experimental.
- PyPy support is described as mostly usable.
Who it suits
Cython suits Python developers who need C extensions, access to C or C++ libraries, or faster C modules. It may also fit projects using NumPy arrays or embedding CPython in existing applications.
Verdict
Cython connects Python code with compiled C and C++ extensions and provides optional typing and cross-language debugging. It requires a C compiler, and some newer interpreter support is still experimental.
Plans and prices
From Cython's own pricing page, checked 30 Sep 2026.
| Plan | Price | What it gives you |
|---|---|---|
| Cython | Free | Freely available under the open source Apache 2.0 License |
The facts
Each one read from Cython's own pages, with the date it was checked.
What it does
- Build requirement
- Cython requires a C compiler; the installation guide gives compiler guidance for Linux, macOS and Windows.checked 30 Sep 2026
- C and C++
- Cython lets Python code call C or C++ code and supports declaring C or C++ types.checked 30 Sep 2026
- Data and libraries
- The project describes using Cython with multidimensional NumPy arrays and integrating with existing low-level libraries and applications.checked 30 Sep 2026
- Debugging
- Cython supports combined source-level debugging across Python, Cython and C code.checked 30 Sep 2026
- Experimental support
- The homepage says support for the CPython Limited API and free-threading CPython is available in Cython 3.1 but considered experimental.checked 30 Sep 2026
- Generated code
- Cython translates source code into C or C++ code that can be compiled as Python extension modules.checked 30 Sep 2026
- Installation
- The documentation recommends installing Cython with pip and says some scientific Python distributions, including Anaconda and Sage, bundle it.checked 30 Sep 2026
- Intended use
- The project identifies wrapping external C libraries, embedding CPython in existing applications and speeding up Python code with fast C modules as use cases.checked 30 Sep 2026
- Python compatibility
- The homepage says generated code compiles with major C and C++ compilers for CPython 3.8 and later, and describes PyPy support as mostly usable.checked 30 Sep 2026
- Static typing
- Optional static type declarations can help generate more efficient C code from Python-like code.checked 30 Sep 2026
- Support channels
- The homepage directs users with questions to the Cython users mailing list and links a separate core developer mailing list.checked 30 Sep 2026
- What it does
- Cython is an optimising static compiler for Python and the extended Cython language, used to write C extensions for Python.checked 30 Sep 2026
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