TypeScript to Flow Converter | Transform TS to Flow Online

🔄 TypeScript to Flow / Declare

Convert TypeScript to Flow types or TypeScript declare definitions (.d.ts).

📝 Input TypeScript Code:
📤 Output:
// Output will appear here...
Types: 0
Interfaces: 0
Properties: 0
💡 Example TypeScript Samples:
📄 Simple Interface
Basic interface definition
🔗 Nested Types
Interface with nested objects
🚀 Advanced Types
Unions, generics, and more

TypeScript to Flow Online Converter

Migrate your codebase effortlessly with our high-performance TypeScript to Flow conversion tool. Maintain type safety while transitioning between ecosystems.

What is TypeScript to Flow Conversion?

As the JavaScript ecosystem evolves, developers often find themselves needing to port libraries or internal projects between different type systems. TypeScript (TS) and Flow share similar goals but utilize different syntax and internal logic.

Our tool automates the tedious process of rewriting syntax, allowing you to focus on logic rather than manual type adjustments.

Key Features of the Converter

  • Real-time Conversion: See your Flow output instantly as you paste your TypeScript code.

  • Interface & Type Alias Support: Seamlessly converts interface and type definitions.

  • Generic Handling: Maintains complex generic structures across both systems.

  • Utility Types: Maps TypeScript utility types (like Partial, Readonly) to Flow equivalents.

Why Convert TypeScript to Flow?

While TypeScript is currently the industry standard, there are specific scenarios where Flow is preferred:

  1. Legacy React Projects: Many early React codebases at scale (like those at Meta) were built with Flow.

  2. Specific Tooling Requirements: Certain internal infrastructures are optimized specifically for Flow’s architecture.

  3. Functional Programming Nuances: Some developers prefer Flow’s approach to nominal vs. structural typing in specific edge cases.

How to Use the TS to Flow Tool

Using our tool is straightforward and requires no installation:

  1. Paste your Code: Copy your TypeScript code into the left-hand editor.

  2. Automatic Processing: The tool will automatically parse the AST (Abstract Syntax Tree) and map it to Flow syntax.

  3. Review and Copy: Check the right-hand editor for the Flow-compatible output and click "Copy" to use it in your project.

Technical Mapping Overview

Our converter handles several critical syntax shifts:

  • Readonly Arrays: Converts ReadonlyArray<T> to $ReadOnlyArray<T>.

  • Optional Properties: Correctly maps prop?: string to prop?: string (while ensuring exact object type compatibility).

  • Enums: Since Flow doesn't have a native enum like TypeScript, it converts them to object constants or union types.

Frequently Asked Questions

Is the conversion 100% accurate?

While we cover 95% of common syntax, some complex TypeScript-specific features (like Decorators or complex Template Literal Types) may require manual adjustment after conversion.

Is my code secure?

Yes. The conversion happens entirely in your browser (client-side). No code is sent to our servers, ensuring your intellectual property remains private.

Can I convert Flow back to TypeScript?

Yes! We also offer a [Flow to TypeScript tool] for developers looking to move in the opposite direction.