The libraries below are inherited from MicroPython. They are similar to the standard Python libraries with the same name. They implement a subset of or a variant of the corresponding standard Python library.

CircuitPython's long-term goal is that code written in CircuitPython using Python standard libraries will be runnable on CPython without changes.

These libraries are not enabled on CircuitPython builds with limited flash memory, usually on non-Express builds: binascii, errno, json, re.

These libraries are not currently enabled in any CircuitPython build, but may be in the future: ctypes, hashlib, zlib.

.. toctree::
   :maxdepth: 1

   builtins.rst
   heapq.rst
   array.rst
   binascii.rst
   collections.rst
   errno.rst
   gc.rst
   hashlib.rst
   io.rst
   json.rst
   re.rst
   sys.rst
   asyncio.rst
   ctypes.rst
   select.rst
   zlib.rst

A few string operations are not enabled on small builds (usually non-Express), due to limited flash memory: string.center(), string.partition(), string.splitlines(), string.reversed().

Functionality specific to the CircuitPython/MicroPython implementation is available in the following libraries. These libraries may change significantly or be removed in future versions of CircuitPython.

.. toctree::
   :maxdepth: 1

   btree.rst
   framebuf.rst
   micropython.rst