JavaScript Minifier

Minifying rewrites JavaScript so it behaves identically but takes fewer bytes. This tool uses Terser, the same minifier behind most modern build tools. It removes comments and whitespace, mangles local variable and function names to one or two letters, and compresses the code itself: it folds constants, removes unreachable branches, inlines single-use variables and joins statements.

Paste code or drop a .js file, choose your options and press Minify (or Ctrl+Enter). The result shows the size before and after. Terser runs in a Web Worker, so even large files do not freeze the page, and your code is processed locally.

• Mangle variable names: shortens local names. Names that are exported or used as object properties are left alone.
• Compress: enables Terser's optimisations, two passes.
• Remove console.* calls: strips debug logging from production builds.
• Keep license comments: preserves comments marked /*! ... */ or containing @license.
• Treat as ES module: enables strict mode and top-level optimisations. Turn it off for classic scripts that rely on top-level var globals.

Input (197 characters):

// Greets a user
function greet(userName, greeting) {
  const message = greeting + ", " + userName + "!";
  console.log(message);
  return message;
}
export const result = greet("world", "Hello");

Output with default options (82 characters):

export const result=function(){const o="Hello, world!";return console.log(o),o}();

Comments and spaces disappeared. Because greet is only called once with fixed arguments, the minifier inlined it and joined the string ahead of time, renamed the local variable to o, and merged the last two statements. The exported name result is untouched, because renaming it would break importers.

• Keep the readable source in version control and treat the minified file as a build artifact. Debugging minified code is painful without a source map; bundlers generate those for you.
• Code that relies on Function.prototype.toString, or on function names for logic, can break when names are mangled.
• On gzip or Brotli-compressed hosting, minification still helps, typically by another 20 to 40 percent over compression alone.
• To make minified code readable again, use the JavaScript beautifier.