Cerberus, or Data Validation for Humans / Nicola Iarocci (CIR 2000, Italy)

Soon or later in their career, every programmer has to deal with data validation. Be it a web, desktop or mobile application, you just cannot avoid data validation. A robust, powerful yet easy-to-use data validation library can be a valuable tool in your toolset. Cerberus is a lightweight and extensible open source data validation library for Python. It provides type checking and other validation, transformation and normalization rules out of the box and it is designed to be easily extensible and customized.