A much more typical experience is to do those 2 steps, and then spend a bunch of time digging through github issues to find the right ignore/suppression incantations to add to your .flowconfig so that your dependencies (including all their transitive deps...) don't break your typechecking. Admittedly this gets easier once you've done it before and know a few reference .flowconfigs to copy/paste like React[1] or babel[2], etc. But this shouldn't be necessary at all. It's been an open issue for 2 years [3].

Less important, but you also have to add /* @flow */ to the top of every single source file. Sure its handy sometimes for existing projects, but it makes little sense for new ones and has also been an issue for years[4].

[1]: https://github.com/facebook/react/blob/65b9ad94aaf62eb61b7b3... [2]: https://github.com/babel/babel/blob/634c750558e5ce149b879b66... [3]: https://github.com/facebook/flow/issues/869 [4]: https://github.com/facebook/flow/issues/284

The fact that flow-bin is a binary which runs as a separate process is the problem. To integrate it with webpack you need to use hacky plugins which are constantly querying the flow server for type errors. With typescript you just use ts-loader and you're done.