Does this work on fully minified, single-line production code?

Yes — that is the primary use case. Paste a minified bundle or a single-line third-party script and it expands into properly indented, multi-line code you can actually trace through.

Will it change my variable names or program logic?

No. Only whitespace and line breaks are added; every identifier, operator, literal value, and piece of logic remains byte-for-byte the same, just reformatted for readability.

How is this different from using source maps in DevTools?

Source maps map minified code straight back to the original, human-written source with original variable names and file structure — the ideal outcome when available. This tool is for the common case where no source map exists (most third-party scripts, ad tags, or older sites) and all you have is the minified file itself.

Can I use this to understand what a suspicious third-party script does?

Yes, this is a reasonable use — beautifying a minified analytics tag, ad script, or embedded widget makes its structure and function calls much easier to scan before you decide whether to trust it on your site.

Will it correctly handle template literals with embedded expressions?

Yes — the tokenizer tracks backtick-delimited template literals as string content, so any braces or brackets used inside a ${...} interpolation are recognized as part of the string context rather than mistaken for code structure that needs indenting.

Does it turn minified code back into exactly what the developer originally wrote?

Not exactly — minification is a one-way process that discards the original variable names, comments, and stylistic choices permanently. Beautifying restores structure and readability, but names like a, b, and n stay as they are; only a source map can recover the true original.

Is it safe to paste proprietary or unreleased code into this tool?

Yes — formatting happens entirely in your browser tab using plain JavaScript string processing. Nothing is uploaded to a server, so internal tools, pre-release code, and anything else you would rather not share externally is safe to beautify here.

Can this help me learn how a library works internally?

Yes — reading beautified source from a library's dist bundle is a common way developers study how a popular package is implemented once the readable indentation makes the control flow and function boundaries visible again.

Does it handle arrow functions, destructuring, and modern ES syntax?

Yes — the formatter works at the character level, tracking only bracket/brace depth and string boundaries, so it does not need to recognize specific syntax forms. Arrow functions, destructured parameters, spread operators, and template literals are all indented correctly because they are still built from the same braces, brackets, and string delimiters the tokenizer already tracks.

Why does the output look different from Prettier or a full AST-based formatter?

This tool reformats based on nesting depth and punctuation, not a parsed abstract syntax tree, so it will not make opinionated style choices like wrapping long argument lists, standardizing quote style, or breaking chained method calls onto separate lines the way Prettier does. It is built for fast, dependency-free readability when the goal is understanding code, not enforcing a house style.

All ToolsJavaScript Beautifier

JavaScript Beautifier

Format and beautify JavaScript code with proper indentation — paste minified JS and get clean, readable code instantly.

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What is JavaScript Beautifier?

JavaScript Beautifier takes minified, bundled, or single-line JS and expands it back into readable code with consistent 2-space indentation based on bracket and brace nesting depth — the reverse of what a build tool does before shipping code to production.

The most common reason to reach for this tool is not writing new code but reading someone else's. Every production website ships minified JavaScript — variable names shortened, whitespace stripped, everything crushed onto as few lines as possible to save bytes over the wire. That is exactly the form you get when you open browser DevTools and look at a bundled vendor script, inspect a third-party analytics or ad snippet, or dig into a node_modules dependency to understand what a library actually does internally before trusting it in your codebase. Minified code is computationally identical to the readable source but is nearly impossible for a human to trace through — a stack trace pointing at line 1, column 48,392 of a single-line file tells you almost nothing until that line is expanded back into real statements.

Beautifying is also a legitimate debugging technique in its own right, separate from source maps. Source maps are the ideal solution when a project ships them, mapping minified line/column positions straight back to original source and giving you full context in DevTools automatically. But plenty of third-party scripts, older sites, and quick investigations do not have source maps available — no build system, no map file, nothing but the minified bundle itself. In that situation, pasting the offending file into a beautifier and re-running it through the browser (or just reading it structurally) is often the fastest way to understand a stack trace, spot a global variable leak, or verify what a suspicious script is actually doing before it runs on your machine.

The formatting logic itself works by tracking nesting depth rather than by full JavaScript parsing — it walks the code character by character, respects string and template literal boundaries (so brackets or semicolons written inside a string are never mistaken for real syntax), and adjusts indentation every time it crosses a { [ or its matching closing counterpart. This means it works on realistic, sometimes slightly irregular code without needing a full AST-based parser, at the cost of not doing deeper things like reordering statements or renaming for style consistency — it changes whitespace only, nothing else, which is exactly what you want when the goal is reading unfamiliar code rather than rewriting it.

How It Works

The formatter scans the input character by character while tracking two things simultaneously: whether it is currently inside a string or template literal (so punctuation inside quotes is never treated as real syntax) and the current bracket/brace nesting depth. Every time it encounters an opening { or [, it emits a newline and increases the indent level by one two-space step; every closing } or ] first decreases the indent level, then emits its own newline before the bracket. Statement terminators (semicolons) and object/array separators (commas) also trigger a line break at the current indent level. Escaped characters inside strings are passed through untouched so a literal backslash-quote never confuses the string-boundary tracking. The entire process runs synchronously in your browser — no code is transmitted anywhere.

How to Use

1
Paste your JavaScript
Paste minified, bundled, or single-line JavaScript into the left editor — a third-party script, a node_modules file, or output copied from browser DevTools all work.
2
Click Beautify JavaScript
The tokenizer scans the code for string and template-literal boundaries and bracket/brace nesting depth, then rebuilds it with consistent 2-space indentation in under a second.
3
Trace the structure
With each statement and block now on its own indented line, scan the nesting to locate the function, conditional, or object relevant to the bug or behavior you are investigating.
4
Copy the formatted output
Click Copy to grab the beautified JavaScript from the right panel and paste it into your editor, a bug report, or your notes.

Who Uses This Tool

🔍

Debugging Minified Code

Expand third-party or bundled JavaScript into readable form so you can step through logic and find bugs.

📦

Inspecting NPM Packages

Beautify source files inside node_modules to understand how a library works before using it.

🎓

Learning from Examples

Reformat minified code samples found online to study the underlying patterns and techniques.

🔄

Code Review Prep

Clean up poorly formatted JavaScript before submitting it for peer review or merging into a repository.

🛠️

Legacy Code Refactoring

Reindent old or auto-generated JavaScript files to make them easier to read and refactor.

📋

Copying Snippets Cleanly

Format a code snippet before pasting it into documentation, a blog post, or a presentation slide.

Why Choose This Tool

Instant Browser Processing

Your JavaScript is formatted entirely in the browser — no server round-trip means results appear in milliseconds.

No Upload Required

Code never leaves your machine, so sensitive business logic and API keys stay completely private.

Handles Minified Input

Designed specifically for minified single-line code, the formatter correctly expands even tightly packed bundles.

String-Safe Parsing

The tokenizer respects string literals so brackets and semicolons inside quotes are never misinterpreted.

Preserves Logic Exactly

Only whitespace and indentation change — variable names, operators, and all logic remain byte-for-byte identical.

One-Click Copy

Copy the entire formatted output to your clipboard with a single button, ready to paste into your editor.

Also Try

JS Compressor CSS Beautifier HTML Beautifier JSON Formatter Regex Tester Base64 Encode/Decode

Key Benefits

Expands minified or single-line JS into readable 2-space-indented code
String- and template-literal-aware — punctuation inside quotes is never misread as syntax
Handles arbitrarily nested functions, objects, and arrays
Changes only whitespace — identifiers, logic, and behavior are untouched
Copy the formatted output with one click
100% browser-based — safe for proprietary or unpublished code

Frequently Asked Questions

Also Known As

javascript beautifier online freeformat javascript code onlinejs code formatter browserbeautify minified javascriptonline javascript indenterpretty print js codeunminify javascript onlinejavascript code formatter no install