Quickly trimming a snippet for inclusion in an HTML bookmarklet or a single-file demo, where you don't have a build chain. Sanity-checking how much "fat" is in a hand-written script before deciding whether a real optimiser is worth setting up. Inlining a small library into a static site without dragging in a bundler.

This is a structural minify, not a compressor. It won't rename variables, dead-code eliminate, mangle properties, or tree-shake. For production builds, use terser , esbuild , or swc in your pipeline — they cut another 30–60% on top of structural minify. ASI traps. JavaScript inserts semicolons in surprising places. The minifier preserves a newline where removing it would change meaning (e.g. return\n{} ≠ return {} ). Stick to explicit semicolons in source if you can — it makes minification safer for everyone. Source maps aren't generated. If you ship minified JS to production, generate source maps with a real toolchain so debugging is sane. Modern compression dominates. Brotli/gzip on the wire does most of what minify does. The biggest wins come from removing unused code — that needs static analysis a structural minifier can't do. Don't minify what you commit. Source goes in pretty; minify at build/deploy.

JavaScript-Minifier

Schnelle JS-Minifizierung — Kommentare entfernen, Whitespace zusammenfassen, Leerzeilen löschen. Größenvergleich inkl.

Eingabe

Ausgabe

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What is this for?

A structural JavaScript minifier strips comments and unnecessary whitespace without changing what the code does. The output is functionally identical to the input — same identifiers, same logic — just shorter. This tool runs that pass in your browser, including the tricky bits: it preserves string contents and regex literals untouched, and keeps newlines where ASI (Automatic Semicolon Insertion) would otherwise change behaviour.

When to use it

Quickly trimming a snippet for inclusion in an HTML bookmarklet or a single-file demo, where you don't have a build chain.
Sanity-checking how much "fat" is in a hand-written script before deciding whether a real optimiser is worth setting up.
Inlining a small library into a static site without dragging in a bundler.

Common gotchas

This is a structural minify, not a compressor. It won't rename variables, dead-code eliminate, mangle properties, or tree-shake. For production builds, use terser, esbuild, or swc in your pipeline — they cut another 30–60% on top of structural minify.
ASI traps. JavaScript inserts semicolons in surprising places. The minifier preserves a newline where removing it would change meaning (e.g. return\n{} ≠ return {}). Stick to explicit semicolons in source if you can — it makes minification safer for everyone.
Source maps aren't generated. If you ship minified JS to production, generate source maps with a real toolchain so debugging is sane.
Modern compression dominates. Brotli/gzip on the wire does most of what minify does. The biggest wins come from removing unused code — that needs static analysis a structural minifier can't do.
Don't minify what you commit. Source goes in pretty; minify at build/deploy.