JavaScript is a dynamically typed language, so the type of a variable is checked during run-time. This property can be useful, however, there are times when developers need static typing. For instance, static typing provides better error checking during compile time.  

TypeScript and Flow are two products that extend JavaScript and aim to solve the lack of static typing in JavaScript and add more functionality.

### About TypeScript

**TypeScript** is an open-source language that was developed by Microsoft and builds on JavaScript -- it is a strict syntactical superset of JavaScript. TypeScript allows the use of classes, modules, and interfaces and adds optional static typing to the language. These features make large-scale development easier. 

### About Flow

**Flow** is a static type-checker for JavaScript developed by Facebook. Unlike TypeScript, it is *not* a language. It is written in OCaml and provides a type-checking system. Since it is not a complete language, it can be easily integrated into JavaScript with a single comment annotation.

# TypeScript vs. Flow

Both TypeScript and Flow are excellent tools that enjoy widespread adoption in the web development community. Nevertheless, TypeScript is more famous than Flow and has a stronger community.  

Both TypeScript and Flow are very similar syntactically and in usage. Both tools have great development features like code refactoring, type debugging, and the ability to smoothly integrate with IDEs.

TypeScript is better supported by popular web development frameworks including Angular and Vue. React supports both TypeScript and Flow, but it integrates better with Flow.

The key differences are highlighted in the table below: 



TypeScript vs. Flow

TypeScript and Flow add static typing to JavaScript, with TypeScript being a full language and Flow a type-checker tool. TypeScript boasts better community support.

TypeScript	Flow
A complete programming language.	Not a programming language, but a flow typing tool.
More features e.g., classes and namespaces.	Less features – it is just a type checker.
Transpiles to JavaScript.	Can be used directly in JavaScript using annotations.
Better documentation.	Documentation sometimes confusing.
Open-source and developed by Microsoft.	Developed by Facebook.