You can also generate PropTypes from your Flow types, which can be useful during development: https://github.com/brigand/babel-plugin-flow-react-proptypes

(Unfortunately it's not working with React Native, but I hope that's fixed soon: https://github.com/brigand/babel-plugin-flow-react-proptypes...)

EDIT: Thanks to namuol, I just discovered flow-runtime: https://codemix.github.io/flow-runtime

This looks amazing!

EDIT 2: flow-runtime also doesn't work with React Native: https://github.com/codemix/flow-runtime/issues/17

That's a shame. I might see if I can fix it, otherwise I'll just stick with compile-time checks for now.