Migrate to TypeScript without rewriting your codebase.
JavaScriptConverter automatically transforms your JavaScript files into typed TypeScript using deterministic AST analysis — not AI guesswork. Handles imports, exports, JSDoc types, class properties, static hoisting, and member accessibility in seconds.
const express = require('express');
/**
* @param {string} name
* @returns {string}
*/
function greet(name) {
return 'Hello ' + name;
}
module.exports = { greet };import express from 'express';
/**
* @param {string} name
* @returns {string}
*/
function greet(name: string): string {
return 'Hello ' + name;
}
export { greet };TypeScript is the industry standard for production JavaScript
Teams adopting TypeScript report fewer production bugs, faster onboarding, and better refactoring confidence. But manual migration is slow and error-prone.
Catch Bugs Before Runtime
TypeScript catches type errors, null references, and API mismatches at compile time instead of in production. Studies show typed codebases have up to 15% fewer bugs.
Better IDE Experience
Get intelligent autocomplete, inline documentation, and jump-to-definition across your entire codebase. TypeScript makes every editor smarter.
Easier Team Collaboration
Type annotations serve as living documentation. New developers understand APIs instantly without reading implementation details.
What JavaScriptConverter actually does
Every transform is a deterministic AST operation — no LLM hallucinations, no random output. The same input always produces the same result.
File Renaming
.js → .ts and .jsx → .tsx with automatic JSX detection in file content.
Import Conversion
require() → import with support for default, named, and destructured imports.
Export Conversion
module.exports → export default and exports.x → named exports.
Type Annotations
Extracts @param and @returns from JSDoc and converts them to inline TypeScript types.
Class Properties
Detects this.x = ... in constructors and generates typed class field declarations.
tsconfig Generation
Automatically generates a tsconfig.json configured for your project's module system and strictness preferences.
Static Property Hoisting
Moves MyClass.prop = value assignments into the class body as static property declarations.
Member Accessibility
Infers private and protected modifiers from naming conventions like _underscore prefixes.
Error Suppression
Adds @ts-expect-error comments for remaining TypeScript errors so converted code compiles immediately.
A simple path from JavaScript to TypeScript
Whether you start in the browser or the desktop app, the workflow is straightforward and designed to minimize surprises.
Choose your workflow
Use the online converter for quick single-file jobs, upload ZIP files for batch conversion via the dashboard, or use the desktop app for full project control.
Deterministic AST transforms
The engine parses your code into an Abstract Syntax Tree and applies each conversion step predictably. No AI randomness — the same input always produces the same output.
Download and refine
Get your converted TypeScript files with full diagnostics. Review the changes, add stricter types where needed, and commit to your repository with confidence.
Online + Desktop
Start with the web converter for quick jobs. Move to the desktop app when you need full project control.
Online Converter
- Paste code and convert instantly
- Upload ZIP for batch conversion
- Dashboard with order history
- No installation required
- Free tier available
Desktop App
Recommended- Drag-and-drop entire folders
- File tree with selective conversion
- Per-file progress and diagnostics
- 100% offline — code never leaves your machine
- Free — no account needed
Frequently Asked Questions
Is this an AI-based converter?
Will the converted code compile without errors?
any types. You may want to enable strict mode gradually and add types manually for complex areas.
What module systems are supported?
require/module.exports) and ES Modules (import/export) are supported. The converter detects CommonJS patterns and transforms them into ES Module syntax. If your code already uses ES Modules, it is preserved as-is.
Is my code sent to a server?
How is this different from just renaming .js to .ts?
Can I convert React/JSX files?
.js and .jsx files and renames them to .tsx accordingly. All import/export and type-inference transforms work the same way with JSX content.
Start your TypeScript migration today
Try the online converter for quick jobs, move to the desktop app for full projects, and scale with batch uploads when you need them.
