JavaScript Beautifier / Formatter
Format and beautify minified JavaScript into clean, readable code with proper indentation.
Why Beautify JavaScript?
Minified JavaScript is designed for machines, not humans. Variable names compressed to single letters, all whitespace stripped, entire libraries on a single line — it's fast to download but impossible to debug. A JS beautifier reverses this process, adding indentation and line breaks so you can actually read the code.
You'll reach for a beautifier when debugging production issues (reading minified error stack traces), reviewing third-party scripts (what does that analytics snippet actually do?), or reformatting code that someone pasted without indentation. It's a development tool you use more often than you'd expect.
This tool handles common JavaScript patterns including strings, objects, arrays, and nested blocks. For advanced formatting with AST-based precision and opinionated style rules, tools like Prettier are better suited. For quick reformatting of minified code, this gets the job done instantly.
JavaScript Formatting Conventions
| Convention | Standard | Why It Matters |
|---|---|---|
| Indentation | 2 spaces (most JS projects) | Keeps deeply nested callbacks and promises readable |
| Semicolons | Required (Standard JS) or omitted (no-semi) | Team preference — be consistent, ASI can cause bugs |
| Quotes | Single quotes (Airbnb) or double (Standard) | Pick one, enforce with a linter, never mix |
| Braces | Same-line opening brace (K&R style) | Nearly universal in JS — Allman style is rare |
| Line length | 80-120 characters | Prevents horizontal scrolling in code review |
| Trailing commas | Required in modern configs | Cleaner git diffs — adding an item doesn't touch the previous line |
What this means for you: Formatting conventions are about consistency, not correctness. The specific choices matter less than everyone on the team following the same rules. Use ESLint + Prettier in your project for automated enforcement.
When to Use Different Formatting Tools
This online beautifier
Quick one-off formatting of minified code, third-party scripts, or code snippets from Stack Overflow. No installation, no configuration, instant results. Best for reading code, not for enforcing style in a project.
Prettier
The industry standard for automated JS/TS formatting. Opinionated (few config options by design), AST-based (understands code structure), integrates with editors and CI. Use this in your actual project.
ESLint --fix
Fixes formatting AND code quality issues. Catches unused variables, missing error handling, and style violations. ESLint + Prettier together give you formatting + linting in one pass.
Browser DevTools
Chrome DevTools has a built-in "Pretty print" button ({}) in the Sources panel. Click it to format any minified script loaded on the page. Great for debugging production issues in real time.
What Beautifying Can't Fix
Beautifying restores readable formatting, but minification is a one-way process for certain transformations:
| Transformation | Reversible? | What You See |
|---|---|---|
| Whitespace removal | Yes | Beautifier adds it back perfectly |
| Comment removal | No | Comments are gone permanently |
| Variable renaming (mangling) | No | calculateTotal → a, readable names are lost |
| Dead code removal | No | Removed code is gone |
| Constant folding | No | 60*60*24 becomes 86400 |
If you're trying to read heavily mangled production code, source maps are a better approach. Source maps link minified code back to the original source with full variable names and comments intact.
Related Tools
How to use this tool
Paste minified or messy JavaScript into the input area
Choose your preferred indentation (2 or 4 spaces)
Click Beautify and copy the formatted result
Common uses
- Reading minified third-party scripts for security review
- Debugging production JavaScript via source inspection
- Reformatting code snippets from Stack Overflow
- Making auto-generated JavaScript readable for editing
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