The JavaScript runtime environment provides your scripts with utility libraries which can be used during execution. It’s your script that references these libraries. The engine itself doesn’t depend on them.
Unlike C and other compiled languages, JavaScript runs in a container. A program reads the JavaScript code and executes it. This program needs to parse the code and convert it into runnable commands. It must also provide objects to JavaScript so that it can interact with other things. The first part is known as the engine, the second is the runtime.
The runtime environment takes on different forms depending on the context. For example, the runtime environment in a web browser is different from that of Node.js. In a web browser, the runtime is comprised of the JavaScript engine, web APIs, the callback queue, and the event loop.
Here are the best free JavaScript runtimes with our verdict captured in a legendary LinuxLinks-style ratings chart. We feature only free and open source software here.
Let’s explore the 14 runtimes. For each program we have compiled its own portal page, a full description with an in-depth analysis of its features, together with links to relevant resources.
| JavaScript Runtime Environments | |
|---|---|
| Node.js | Hugely popular cross-platform JavaScript run-time environment |
| Bun | Fast JavaScript runtime designed as a drop-in replacement for Node.js. |
| Deno | Simple, modern and secure runtime for JavaScript and TypeScript |
| WasmEdge | High-performance, and extensible WebAssembly runtime |
| workerd | JavaScript and WebAssembly server runtime |
| LLRT | Designed for fast, resource-efficient serverless applications |
| txiki.js | Small and powerful JavaScript runtime |
| JerryScript | JavaScript engine for the Internet of Things |
| GraalJS | ECMAScript-compliant JavaScript engine |
| Window.js | JavaScript runtime for desktop graphics programming |
| Blueboat | Multi-tenant serverless JavaScript runtime |
| lo | Successor project to Just |
| StarlingMonkey | SpiderMonkey-based JavaScript runtime |
| Just | Very small v8 JavaScript runtime |
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