Crab is a Python framework for building recommendation engines. It began as a community-driven project one year ago and was incorporated into the open-source labs Muriçoca in April 2011. Crab is being rewritten as a Scikit (toolkit for machine learning in Python) to take advantage of the Scikit-Learn algorithms and infrastructure. The current version of Crab implements collaborative filtering algorithms like user-based, item-based, and matrix factorization and can evaluate recommender algorithms with metrics like precision, recall, and RMSE. It also provides APIs to build recommendation systems and deploy them using REST frameworks. Crab is already used in some production recommender systems.