Open-source static type checker for JavaScript, developed at Meta, designed for gradual adoption in large codebases.
Flow is a static type system for JavaScript created at Meta. It checks JavaScript code for type errors using a combination of type inference and optional annotations, so existing code can adopt typing incrementally without being rewritten.
Flow is free and open source, distributed through npm and usable alongside existing JavaScript build tooling. Meta reports using Flow across millions of JavaScript files, and the project presents itself as a direct alternative to TypeScript for teams that want static typing for JavaScript with minimal changes to their development workflow.
Dart
google.com
ReScript
ReScript — strongly typed programming language
rescript-lang.org
Microsoft
TypeScript
microsoft.com
Adds products that compete with one of Flow’s direct competitors but not with Flow itself. They are shaded, and Linked Through names the direct competitor each one competes with.
| Attribute | Flow | Dart | ReScript — strongly typed programming language | TypeScript | |
|---|---|---|---|---|---|
| Provider | |  | |  | |
| Founded | 2004 | 1998 | 2020 | 1975 | |
| Sells To | Consumers, Enterprise | Enterprises, Individuals | Developers | Enterprises, Small Business | |
| Pricing Model | Advertising | Advertising, Subscription | Open Source | SaaS, Transactional | |
| Ownership | Public | Subsidiary | — | Public |
Provider
Founded 2004
Sells To Consumers, Enterprise
Pricing Model Advertising
Ownership Public
Provider
Founded 1998
Sells To Enterprises, Individuals
Pricing Model Advertising, Subscription
Ownership Subsidiary
Provider
Founded 2020
Sells To Developers
Pricing Model Open Source
Ownership —
Provider
Founded 1975
Sells To Enterprises, Small Business
Pricing Model SaaS, Transactional
Ownership Public
Cross-platform JavaScript runtime environment for executing server-side JavaScript code.
Open-source UI framework from Google for building natively compiled applications for mobile, web, desktop, and embedded platforms.
Cross-platform JavaScript runtime environment for executing server-side JavaScript code.
Swift is Apple's general-purpose programming language for apps across its platforms and servers.
Kotlin is the open-source programming language created by JetBrains for the JVM, Android, JavaScript, and native targets.
