python2ts

Transpile Python to TypeScript — Automatically

Stop rewriting Python code by hand. python2ts transforms your Python into clean, idiomatic TypeScript — with full type preservation.

Install

npm install -g python2ts

Usage

# Transpile a file
python2ts algorithm.py -o algorithm.ts

# Transpile to stdout
python2ts script.py

# Pipe from stdin
cat utils.py | python2ts > utils.ts

What It Does

Your Python

from dataclasses import dataclass
from collections import Counter

@dataclass
class WordStats:
    text: str

    def word_count(self) -> dict[str, int]:
        words = self.text.lower().split()
        return dict(Counter(words))

    def most_common(self, n: int = 5):
        counts = Counter(self.word_count())
        return counts.most_common(n)

Clean TypeScript

import { Counter } from "pythonlib/collections"

class WordStats {
  constructor(public text: string) {}

  wordCount(): Map<string, number> {
    const words = this.text.toLowerCase().split(/\s+/)
    return new Map(new Counter(words))
  }

  mostCommon(n: number = 5) {
    const counts = new Counter(this.wordCount())
    return counts.mostCommon(n)
  }
}

Supported Python Features

| Feature | Example | Output | | ------------------------ | ----------------------------- | --------------------------------------------- | | Type hints | def foo(x: int) -> str: | function foo(x: number): string | | Dataclasses | @dataclass class Point: | class Point { constructor... } | | List comprehensions | [x*2 for x in items] | items.map(x => x * 2) | | Dict comprehensions | {k: v for k, v in pairs} | new Map(pairs.map(...)) | | Pattern matching | match x: case 1: ... | switch/if statements | | f-strings | f"Hello {name}!" | `Hello ${name}!` | | Async/await | async def fetch(): | async function fetch() | | Decorators | @lru_cache def fib(n): | Transformed decorators | | Context managers | with open(f) as file: | try/finally blocks | | Generators | yield from items | yield* items | | Walrus operator | if (n := len(x)) > 0: | let n; if ((n = len(x)) > 0) | | Multiple inheritance | class C(A, B): | Mixins | | Standard library | from itertools import chain | import { chain } from "pythonlib/itertools" |

CLI Options

Usage: python2ts [options] [file]

Arguments:
  file                    Python file to transpile (reads from stdin if omitted)

Options:
  -o, --output <file>     Write output to file instead of stdout
  -r, --runtime <path>    Custom runtime library path (default: "pythonlib")
  --no-runtime            Don't add runtime imports
  -v, --version           Show version number
  -h, --help              Show help

Programmatic API

import { transpile } from "python2ts"

const python = `
def greet(name: str) -> str:
    return f"Hello, {name}!"
`

const typescript = transpile(python)
console.log(typescript)
// function greet(name: string): string {
//   return `Hello, ${name}!`
// }

Runtime Library

The transpiled code uses pythonlib for Python standard library functions. Install it as a dependency in your project:

npm install pythonlib

Documentation

| Resource | Description | | ------------------------------------------------------------------------------ | ------------------------------ | | Homepage | Project overview and features | | Getting Started | Installation and first steps | | Syntax Reference | Complete transformation rules | | API Reference | Programmatic API documentation |

Runtime Support

Transpiled code runs everywhere JavaScript runs:

• Node.js (v22, v24)
• Bun
• Deno
• Browsers
• Edge (Cloudflare Workers, AWS Lambda, Vercel)

Related

• pythonlib — Python standard library for TypeScript
• GitHub — Source code, issues, contributions welcome

License

MIT © Sebastian Software GmbH