JavaScript Pretty Print Online — Format JS Code

Unlike a full opinionated formatter (Prettier, Standard, Biome) which re-prints the entire AST and may change quote style or trailing commas, a pretty printer preserves your token order and only restores whitespace. It is purely additive — your JS continues to behave identically because whitespace outside strings does not affect parsing.

How to pretty print JavaScript — 4 steps

1. Paste your JavaScript. Copy minified bundle output, a one-line snippet from DevTools, or any JS source into the Input panel. Click Load Sample to try a demo.
2. Click Run. The pretty printer processes the code client-side and adds indentation and line breaks.
3. Review the output. The Output panel shows beautified JavaScript ready to read or step through.
4. Copy the result. Click Copy to paste the formatted code into your editor, a snippet, or a code review.

Side-by-side: minified input vs pretty-printed output

function calc(items){let total=0;for(const i of items){if(i.active){total+=i.price*i.qty;}}return total;}

function calc(items) {
  let total = 0;
  for (const i of items) {
    if (i.active) {
      total += i.price * i.qty;
    }
  }
  return total;
}

Common use cases

• check_circlePretty print a minified production bundle (webpack, Vite, esbuild) to debug a runtime error
• check_circleReformat JavaScript copied from Chrome DevTools or Firefox Console for analysis
• check_circleUnminify a third-party library to understand its public API or behaviour
• check_circleBeautify obfuscated JS to inspect a script flagged by a security review
• check_circleFormat auto-generated JS from a code generator before committing to a repo
• check_circleClean up JavaScript snippets pasted from documentation or tutorials
• check_circleReformat a one-line bookmarklet or DevTools snippet to make it editable
• check_circlePretty print legacy concatenated JS files before a refactor or modularisation pass

Pretty print vs Prettier vs js-beautify

A pretty printer is the lightweight option: it preserves your token order and only adds whitespace, so the diff is purely additive. js-beautify is similar but more configurable. Prettier goes further — it re-prints the AST, normalises quotes, enforces line length, and applies trailing commas. For a one-off readability pass on a minified file, a pretty printer is the fastest tool. For project-wide enforcement, configure Prettier in package.json and a pre-commit hook so every file is formatted before it lands in version control.