Unknown security vulnerabilities

Kybra is a beta project using a new Python interpreter. See the disclaimer for more information.

No C extensions

Any PyPI packages or other Python code that relies on C extensions will not currently work. It is a major goal for us to support C extensions in the future.


Kybra is probably ~7-20x less performant than what you would expect from CPython. We hope to eventually use CPython as Kybra's underlying Python interpreter.

Do not use dictionary unpacking

A bug in the RustPython interpreter means that dictionary unpacking should not be used until this issue is addressed.

You should use ic.print instead of print.

Kybra types


Make sure to use the from kybra syntax when importing types from the kybra module, and to not rename types with as:


from kybra import Record

class MyRecord(Record):
    prop1: str
    prop2: int


import kybra

class MyRecord(kybra.Record):
    prop1: str
    prop2: int


from kybra import Record as RenamedRecord

class MyRecord(RenamedRecord):
    prop1: str
    prop2: int

We wish to improve this situation in the future to handle the many various ways of importing.

Treatment as keywords

You should treat Kybra types essentially as keywords, not creating types of the same name elsewhere in your codebase or in other libraries. Any types exported from this file should be treated thusly.