OpenML is an online platform and service for machine learning, whose goal is to make machine learning and data analysis simple, accessible, collaborative and open with an optimal division of labour between computers and humans. People can upload and share data sets and questions (prediction tasks) on OpenML that they then collaboratively solve using machine learning algorithms. It is accessible to everyone for free. It can be used to download or upload OpenML data such as datasets and machine learning experiment results. It provides easy access to all datasets, tasks and experiments on OpenML from within Python.