Windows Support is Here!

We are excited to announce that Flow is now officially available on 64-bit Windows! Starting with Flow v0.30.0, we will publish a Windows binary with each release. You can download the Windows binary in a .zip file directly from the GitHub releases page or install it using the flow-bin npm package. Try it out and report any issues you come across!


Getting Flow working on Windows was not easy, and it was made possible by the hard work of Grégoire, Çagdas and Fabrice from OCamlPro.

Getting Started with Windows

Getting Started with flow-bin on Windows

Does your JavaScript project use npm to manage dependencies? Well, then the easiest way for you to install Flow is with npm! Just run

> npm install --save-dev flow-bin

(Note: on Windows, it is recommended to use npm v3, to avoid the long node_modules paths that npm v2 creates)

This will install the flow-bin npm package and automatically add it to your package.json. Once installed, there are a few ways to use the Flow binary. One is to use ./node_modules/.bin/flow directly. For example, every Flow project needs a .flowconfig file in the root directory. If you don't already have a .flowconfig, you could create it with Powershell, like

> New-Item .flowconfig

or you could run the flow init command, using ./node_modules/.bin/flow

> ./node_modules/.bin/flow init

Another way to run Flow is via an npm script. In your package.json file, there is a "scripts" section. Maybe it looks like this:

"scripts": {
  "test": "make test"
}

You can run the Flow binary directly from a script by referencing flow in a script, like so:

"scripts": {
  "test": "make test",
  "flow_check": "flow check || exit 0"
}

and then running that script via npm run

> npm run flow_check

(Note: the || exit 0 part of the script is optional, but npm run will show an error message if the script finishes with a non-zero exit code)

You can also install flow-bin globally with

> npm install --global flow-bin

Getting Started with flow.exe

Each GitHub release of Flow starting with v0.30.0 will have a zipped Windows binary. For example, the v0.30.0 release includes flow-win64-v0.30.0.zip. If you download and unzip that, you will find a flow/ directory, which contains flow.exe. flow.exe is the Flow binary, so if you put that somewhere in your path, and you should be good to go.

> mkdir demo
> cd demo
> flow.exe init
> "/* @flow */ var x: number = true;" | Out-File -Encoding ascii test.js
> flow.exe check
test.js:1
  1: /* @flow */ var x: number = true;
                                 ^^^^ boolean. This type is incompatible with

  1: /* @flow */ var x: number = true;
                        ^^^^^^ number