JS Minifier

Removing whitespace and comments is the easy, obvious part of minification — and on its own it barely moves the needle on well-written code. The real size reduction comes from two deeper transformations: mangling, which renames every local variable and function argument to the shortest possible identifier (`accumulator` becomes `a`, `temporaryResult` becomes `t`), and dead-code elimination, which removes branches and expressions that a static analysis of the code can prove will never execute or never affect output. Both require actually understanding the code's structure — its scopes, which names are local versus exported, which branches are provably unreachable — which is why a real parser-based tool like Terser produces meaningfully smaller output than a naive find-and-replace over whitespace ever could.

Bundlers like Webpack, esbuild, Rollup and Vite minify their output automatically as part of a production build, almost always using Terser or a Terser-compatible engine under the hood — so for anyone working inside a modern JavaScript project, minification already happens invisibly every time they run a build command. A standalone tool like this one covers the cases that fall outside that pipeline: a single script tag with no build step, a quick check of how much a snippet would shrink, or a one-off file that needs compressing without pulling in an entire bundler configuration just for that purpose.

Minifying and formatting are opposite operations on the same code: this tool strips out the whitespace, structure and readability that a formatter like Prettier deliberately adds back in. Its sibling tool, the JavaScript Formatter, undoes exactly what this one does — useful for the reverse direction, taking a minified file someone handed you and turning it back into something readable enough to actually debug.

A real build pipeline normally pairs minification with a source map — a separate file that maps every position in the minified output back to its original line in the source — specifically so a debugger can still show readable code and correct line numbers in production, despite the file actually running being unreadable. This standalone tool intentionally does not generate one, since it is meant for a quick one-off shrink rather than a production deployment; anything going into a real build pipeline should go through a bundler that emits a matching source map alongside it.