Unfragile

The request names SpiderMonkey, Mozilla's JavaScript and WebAssembly engine, so it comes first 1; it can be embedded in C++ and Rust projects or run as a stand-alone shell 1. If you need a different JavaScript engine, V8 is Google's open-source high-performance JavaScript and WebAssembly engine, used in Chrome and Node.js 4, and Node.js is a cross-platform JavaScript runtime for servers, web apps and command-line tools 5.

1
SpiderMonkeyspidermonkey.devwebsite read, tools not yet checked
Mozilla's JavaScript and WebAssembly engine, written in C++ and Rust, that can be embedded in C++ and Rust projects or run as a stand-alone shell 1.
Website Docs
2
V8 JavaScript enginev8.devfound in code, not yet checked
Google's open-source JavaScript and WebAssembly engine, written in C++, used in Chrome and Node.js and embeddable in any C++ application 4.
Website Docs
for agents: jsb_run_bench · ecma262_parse · run_d8
3
Node.jsnodejs.orgwebsite read, tools not yet checked
A free, open-source, cross-platform JavaScript runtime for building servers, web apps, command-line tools and scripts 5.
Website Docs
+58 community tools built for it
4
Servoservo.orgwebsite read, tools not yet checked
A web rendering engine written in Rust, with WebGL and WebGPU support, adaptable to desktop, mobile and embedded applications 6.
Website

Sources

1Home | SpiderMonkey JavaScript/WebAssembly Enginespidermonkey.dev · read 2026-10-29
4V8 JavaScript enginev8.dev · read 2026-10-29
5Node.js — Run JavaScript Everywherenodejs.org · read 2026-10-29
6Servo aims to empower developers with a lightweight, high-performance alternative for embedding web technologies in applications.servo.org · read 2026-10-29

For agents: the 10 actions behind this answer

· Spidermonkey website read, tools not yet checked
SpiderMonkey is Mozilla’s JavaScript and WebAssembly Engine, used in Firefox, Servo and various other projects. It is written in C++ and Rust.
JavaScript · ClearScript Library for Windows (x86/x64) verified and signed
· Playwright website read, tools not yet checked
Web automation and testing for apps, scripts, and AI agents
jsb_run_bench · agents found in code, not yet checked
Run a JetStream2/3 story with one or more JS shell binaries and return scores.
· Node.js website read, tools not yet checked
Node.js® is a free, open-source, cross-platform JavaScript runtime environment that lets developers create servers, web apps, command line tools and scripts.
· Servo Smallvec website read, tools not yet checked
Servo is a web rendering engine written in Rust, with WebGL and WebGPU support, and adaptable to desktop, mobile, and embedded applications.
· Servo Url website read, tools not yet checked
Servo is a web rendering engine written in Rust, with WebGL and WebGPU support, and adaptable to desktop, mobile, and embedded applications.
node · discord.js verified and signed
· Servo Form Urlencoded website read, tools not yet checked
Servo is a web rendering engine written in Rust, with WebGL and WebGPU support, and adaptable to desktop, mobile, and embedded applications.
· Servo Idna website read, tools not yet checked
Servo is a web rendering engine written in Rust, with WebGL and WebGPU support, and adaptable to desktop, mobile, and embedded applications.

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