One thing I like about Flow for small projects is that you can use the Flow 'comment syntax' so that you can start using Flow and leaning on the typechecker without adding any transpilation setup at all. Flow's inference means many type annotations can safely be omitted, too. Example: https://github.com/jsdf/they-live/blob/master/handler.js#L11...

I find this especially useful for node projects, where there is less of a case for using Babel etc (node 7 supports all the JS features I want).