JavaScript Formatter & Minifier
Format or minify JavaScript safely: parsed, never executed, in a worker.
Browser onlyYour data never leaves this device.
Runs entirely in your browser. Your code never leaves this device and is never stored or executed.
Details: Privacy policy
Input
Runs on demand in a worker. Never executed.
Result
No result yet.
Fill the field above and press Transform.
JavaScript Formatter and Minifier formats or minifies JavaScript by parsing it, never by running it, and the distinction is the point: your code is data here, not a program. It will beautify a single-line function lifted out of a production bundle so you can read what it does, or minify a finished snippet so it fits in a field with a size limit. Because the code is parsed rather than executed, a syntax error is reported with its position instead of breaking the page, and nothing in the file runs during the operation. The work happens in a background worker with a fifteen-second ceiling, so a pathological input is terminated rather than left to hang the tab. Input is capped at a million characters. Source maps are out of scope: the transformed code is returned as written, with no mapping back to the original. Everything stays in your browser, and nothing is uploaded or stored. The output is plain source text, so it can be copied into an editor or a diff without any wrapper, and the page keeps the original and the result side by side so the change can be inspected before it is used. Formatting a minified bundle back out is the common case, and because the worker parses rather than evals, a syntax error is reported with nothing executed and no source map invented. A job that exceeds fifteen seconds in the worker is abandoned rather than allowed to hold the interface, and the one-million-character ceiling is checked before parsing begins.
How to use JavaScript Formatter & Minifier
- Paste JavaScript and pick format or minify plus an ECMAScript target.
- Run the transform and review the byte delta.
- Copy or download the result, or clear to start over.
What you get
- Formatted or minified JavaScript, produced by parsing the code rather than running it.
- Syntax errors reported with their position, and nothing executed in either mode.
- The transformed source alone, with a note that source maps are out of scope.
When to use JavaScript Formatter & Minifier
- Beautify single-line JavaScript copied from a bundle before reading it.
- Minify a finished snippet for pasting into a size-constrained field.
- Read a single-line function lifted out of a production bundle by formatting it, without executing the bundle.
Frequently asked questions about JavaScript Formatter & Minifier
Does the JavaScript tool upload or run my code?
Neither. Terser parses your code locally in a background worker on this device; nothing is sent anywhere and nothing is ever executed.
What happens with a syntax error?
The parser reports the position and a short reason before anything is emitted. Your input is left untouched.
Can a hostile input freeze my browser?
No. Jobs run off the main thread with a 15-second timeout and a cancel button; runaway parses are terminated with a clear message.
Are source maps generated?
No. Source maps are explicitly out of scope: the tool returns transformed code only.
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