JS to TypeScript — Free Online Tool

Add TypeScript type annotations to JavaScript functions for better type safety and IDE support. JS to TypeScript is a free online tool from the ToolsRift JavaScript Tools collection. It runs entirely in your browser — nothing to install, no signup, and your data never leaves your device.

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How to use JS to TypeScript

  1. Open the JS to TypeScript above — it loads instantly, no account needed.
  2. Enter or upload your input. Everything is processed locally on your device.
  3. Get your result immediately and copy or download it with one click.

Frequently asked questions

What TypeScript features are added?

The tool adds basic type annotations to function parameters and return types, converts var to let/const, and adds interface suggestions.

Is the output production-ready TypeScript?

The output is a starting point. You'll need to refine types, add generics, and handle edge cases for production TypeScript code.

Do I need to know TypeScript to use this?

Basic TypeScript knowledge helps. The tool generates simple type annotations that you can then customize and improve.

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