babel-plugin-flow-to-typescript

Babel plugin to convert Flow type annotations into TypeScript. Current stable version: 0.6.0. Release cadence is low (last release June 2018). Key differentiator: transforms Flow syntax (exact types, opaque types, $Keys, etc.) directly in Babel pipeline. No type inference, but covers most Flow constructs including maybe types, function types, object types, and utility types like $Diff and $Shape. Requires @babel/core ^7.4.4. Not actively maintained; no support for newer Flow features or TypeScript 3+ syntax.