[AgentME]

If you have an existing codebase already using Babel and Webpack or Browserify, then using Flow only requires tweaking Babel's config a little (or not at all if you're already using the React preset). You use Flow like a linter tool. It doesn't try to take over your build process; You don't have to leave Babel and Webpack/Browserify behind. Flow is also great for allowing you to gradually add typing to an application.