Dev tools · alternatives · 2026

This tool allows developers to safely execute user-generated JavaScript code in the browser by running it in a web worker on a separate domain, isolating it from the main site. It's designed for developers building… Below are 24 products that do a similar job, ranked by how close each is in meaning and then by launch-day votes. Run unsafe user generated JavaScript in the browser launched in 2022; newer entries below may have overtaken it.

1. 1
   Execute JavaScript in a WebAssembly QuickJS sandbox▲206

   This TypeScript package allows you to safely execute JavaScript code within a WebAssembly sandbox using the QuickJS engine. Perfect for isolating and running untrusted code securely, it leverages the lightweight and fast QuickJS engine compiled to WebAssembly, providing a robust environment for code execution. Features - *Security*: Run untrusted JavaScript code in a safe, isolated environment. - *File System*: Can mount a virtual file system - *Custom Node Modules*: Custom node modules are mountable - *Fetch Client*: Can provide a fetch client to make http(s) calls - *Test-Runner*: Includes…

   2024 · github.com · its alternatives →

2. 2SJ
   Sandbox.js - Run user code in a sandboxed environment▲31

   2012 · engineering.versal.com · its alternatives →

3. 3
   I made a CLI tool to create web extensions with no build configuration▲381

   Hello HN! I'm the creator and solo developer of Extension.js, a development tool for browser extensions with built-in support for TypeScript, WebAssembly, React, and modern JavaScript. Developers use it to spend less time configuring the compilation config or learning new frameworks and more time actually writing code. Most projects similar to Extension.js rely on some sort of abstraction or configuration to get started, making the initial development process slow given the extra learning curve and setup guidelines. By using Extension.js, adding the package to your npm scripts is all it…

   2024 · github.com · its alternatives →

4. 4IW
   I wrote a .NET to JS compiler. Here's an XNA demo compiled to JS.▲103

   2011 · hildr.luminance.org · its alternatives →

5. 5
   I've been making JavaScript sandbox alone for 6 years▲397

   Hi HN! Thanks for your attention to my post. It was a big challenge to run most of Node.js packages in browser, fast moreover. Virtual File system, resolve import/export. I got cold many times, depressions, burned out, yet still alive and finished it. Many guys helped me with an advice. Many users give a lot of positive feedback. There are 200,000 monthly unique users. I work full time now because of the freemium business model. To be honest - I am happy after many years of hard work.

   2022 · playcode.io · its alternatives →

6. 6SU
   Speed up your site by running JavaScript when the browser is idle▲94

   2022 · npmjs.com · its alternatives →

7. 7WG
   Write Go code in JavaScript files▲158

   I built a Vite plugin that lets you write Go code directly in .js files using a "use golang" directive. It compiles to WebAssembly automatically.

   Oct 2025 · npmjs.com · its alternatives →

8. 8BB
   Browser based deep fakes in pure JavaScript▲117

   2021 · filter.mot.omg.lol · its alternatives →

9. 9MT
   My Turbo Pascal compiler in JavaScript▲101

   2013 · teamten.com · its alternatives →

10. 10
    CustomJS▲143

    Hello, as an Indie Hacker, I have built and successfully launched this SaaS software. Originally it was a plugin for Make.com but now it can also be used for many other user cases. It's a niche market but many users are enjoying it. Feel free to give me more feedback https://www.customjs.space

    2024 · customjs.space · its alternatives →

11. 11
    Paper Programs – Run JavaScript on pieces of paper▲235

    Run Javascript programs on pieces of paper, using a projector and camera. Physically hold programs in your hand, and see them come to life, as if by magic.

    2018 · paperprograms.org · its alternatives →

12. 12
    Kyushu – A self-hostable WASM sandbox for JavaScript workers▲89

    A self-hostable Wasm sandbox for JavaScript workers.

    Jun 2026 · kyushu.dev · its alternatives →

13. 13CJ
    Codeblock.js - Editable, runnable javascript code blocks▲50

    2013 · filepicker.github.io · its alternatives →

14. 14
    BrowserBox – do stuff with browsers that you can't normally▲134

    💚🇺🇸🗽Secure remote browsing anywhere, any way you like it. - GitHub - BrowserBox/BrowserBox: 💚🇺🇸🗽Secure remote browsing anywhere, any way you like it.

    2023 · github.com · its alternatives →

15. 15
    Instant API – Build type-safe web APIs with JavaScript▲102

    Hey there HN! I just wrapped up an all-day documentation spree for Instant API, a JavaScript framework for easily building web APIs that implements type safety at the HTTP interface. It uses a function-as-a-service approach combined with a slightly modified JSDoc spec to automatically enforce parameter and schema validation before HTTP requests make it through to your code. You just write comments above your endpoint functions and voila, enforced type safety contracts between your API endpoints and your developers. OpenAPI specifications are generated automatically as a byproduct of simply…

    2023 · github.com · its alternatives →

16. 16
    Runno▲148

    Make embeddable code snippets that run in the browser

    2021 · runno.dev · its alternatives →

17. 17
    Auto-generate vanilla JavaScript alternatives for jQuery methods▲137

    Automatically finds jQuery methods from existing projects and generates vanilla js alternatives. - sachinchoolur/jquery-to-javascript-converter

    2021 · github.com · its alternatives →

18. 18
    Mystral Native – Run JavaScript games natively with WebGPU (no browser)▲50

    Hi HN, I've been building Mystral Native — a lightweight native runtime that lets you write games in JavaScript/TypeScript using standard Web APIs (WebGPU, Canvas 2D, Web Audio, fetch) and run them as standalone desktop apps. Think "Electron for games" but without Chromium. Or a JS runtime like Node, Deno, or Bun but optimized for WebGPU (and bundling a window / event system using SDL3). Why: I originally started by starting a new game engine in WebGPU, and I loved the iteration loop of writing Typescript & instantly seeing the changes in the browser with hot reloading. After…

    Jan 2026 · github.com · its alternatives →

19. 19
    Online JS Compiler▲2

    Run JavaScript instantly in your browser - no setup needed

    Feb 2026 · online-js-compiler.vercel.app · its alternatives →

20. 20
    WebContainer API▲121

    Dev environments, in your web app

    2023 · webcontainers.io · its alternatives →

21. 21CJ
    CMS.js – Fully Client-Side JavaScript Site Generator▲117

    2016 · cdmedia.github.io · its alternatives →

22. 22
    Free open-source isolated browser for security▲71

    💚🇺🇸🗽Secure remote browsing anywhere, any way you like it. - GitHub - BrowserBox/BrowserBox: 💚🇺🇸🗽Secure remote browsing anywhere, any way you like it.

    2021 · github.com · its alternatives →

23. 23AP
    A playground for in-browser interpreters▲79

    2015 · fatiherikli.github.io · its alternatives →

24. 24
    To-Userscript: Chrome Extension to Userscript Converter▲42

    Convert browser extensions to userscripts. Contribute to Explosion-Scratch/to-userscript development by creating an account on GitHub.

    2025 · github.com · its alternatives →

Ranked by how close each launch is in meaning, then by votes. Prices were read from each product’s own site when checked and can change. Refine with your own description →