We picked Flow because we were using React, and Flow was from Facebook, so we assumed the support/integration would be tighter than with TypeScript. It also had

We picked Flow because we were using React, and Flow was from Facebook, so we assumed the support/integration would be tighter than with TypeScript. It also had some appealing goals like stronger soundness, and a greater emphasis on type inference than TypeScript had at the time The main reason we switched was the tooling. The language server was slow in the best of times, would crash constantly, would memory-leak all over the place. Some of our devs stopped running it at all because it was so broken all the time. Then I tried out TypeScript and the speed and stability were breathtaking, and we never looked back.