At the time of writing, the Reason toolchain is essentially BuckleScript—Reason's partner project—and the familiar JavaScript toolchain, namely npm and webpack (or another JavaScript module bundler).
There's no longer a need for babel, since BuckleScript compiles to the ES5 version of JavaScript. The compiled output can be configured to use either the CommonJS, AMD, or ES module formats. Reason's powerful static-type system replaces the need for Flow and ESlint. Additionally, Reason's editor plugins all come with refmt, which is essentially prettier for Reason.