[1] Many implementations of ECMAScript engines are available, which differ based on the platforms they are intended to support, their level of conformance, and other implementation-specific characteristics.
This article attempts to provide a relatively comprehensive list of engines that execute ECMAScript code.
The uses of the listed engines vary widely; some of these are engines intended for browsers that can run ECMAScript code on websites that include ECMAScript, like V8 (used in both Google Chrome and Node.js) and SpiderMonkey; some are intended for specific platforms (like Tamarin, Espruino, Rhino, Nashorn, and GraalJS).
Web browsers that support JavaScript embed JavaScript engines in order to support JavaScript-enabled web pages.
Some engines either power JavaScript in obsolete browsers (like Internet Explorer), or have subsequently been replaced (as the engine has in Opera, with its move to Chromium).