JavaScript Beautifier - Format JS Code Online

Format and beautify your JavaScript instantly with our free JavaScript Beautifier. This tool adds proper indentation, line breaks, and consistent spacing to minified or messy JS so it becomes readable and easy to debug. Perfect for front-end developers, Node.js engineers, and anyone inspecting bundled or machine-generated code. Simply paste your compressed JavaScript and get a neatly formatted version in seconds.

Beautifying (also called JS formatting or pretty-printing) parses your script and re-emits it with consistent indentation so the structure of functions, blocks, and statements is obvious at a glance — invaluable for understanding a library's source, reviewing a teammate's code, or recovering readable code from a minified bundle. It is the reverse of minification, so it pairs perfectly with the JavaScript Minifier when you need to switch between readable source and compact output.

The formatter runs in real time and entirely in your browser — there is no signup and nothing is uploaded. Each block opens on its own line, statements are placed on individual indented lines, and braces line up so the code hierarchy is easy to scan.

Live Example

Here is a small minified function before and after beautifying. The logic is unchanged — only the indentation, line breaks, and spacing are added:

function greet(name){const message='Hello, '+name+'!';return message;}

function greet(name) {
  const message = 'Hello, ' + name + '!';
  return message;
}

How to Use JavaScript Beautifier

1. Open the tool: Click Try It to launch the two-pane editor.
2. Paste Your JavaScript: Enter or paste your minified or unformatted JS into the input area on the left.
3. Beautify Automatically: The tool adds nested indentation, line breaks, and consistent spacing while preserving your strings, comments, and logic.
4. Review the Output: Read your clean, well-structured script in the syntax-highlighted output panel.
5. Copy or Download: Copy the beautified JavaScript to your clipboard or download it as a .js file.

Key Features

• Nested indentation: every statement inside a block is indented one level, and closing braces align with their opener.
• One statement per line: semicolons end a line so each statement is easy to read and review.
• Consistent spacing: spaces are added around operators and after commas, while calls like foo() stay tight.
• String- and regex-safe: content inside quotes, template literals, and regular expressions is preserved exactly.
• Syntax highlighting: the output panel colors your code so keywords, strings, and numbers stand out.
• Copy or download: grab the beautified JS to your clipboard or save it as a .js file.
• 100% private & client-side: everything runs in your browser — nothing is uploaded or stored.

Common Use Cases

• Reverse minification: Turn a minified production bundle back into readable code so you can understand what it does.
• Code review: Reformat dense, single-line JavaScript so teammates can review it easily.
• Debugging: Indent nested blocks to spot mismatched braces and stray semicolons quickly.
• Learning: Make compact examples from tutorials or books readable so you can follow the logic.
• Inheriting third-party code: Make sense of a minified library script before customizing or extending it.

About JavaScript Beautification

JavaScript beautification (or formatting / pretty-printing) rewrites a script with consistent indentation and line breaks so a human can read it. JavaScript source is organized as a series of statements grouped into blocks with braces, and those blocks can nest arbitrarily deep — functions inside objects inside loops inside modules. Indentation makes that nesting visible: statements sit one level deeper than their enclosing block, and a closing brace lines up with the line that opened the block. The JavaScript engine ignores almost all whitespace, which is exactly why production JS is usually minified — but humans need that whitespace back to understand, debug, and review the code.

A beautifier works by tokenizing the source: it splits the text into strings, template literals, regular expressions, comments, numbers, identifiers, operators, and punctuation, while protecting the contents of strings and regex so internal spaces and slashes are never misread. It then walks the tokens tracking brace depth. When it meets an opening brace it writes the line and steps in a level; at a semicolon it ends the statement; and at a closing brace it steps out a level and aligns it. Because it never evaluates the code, a beautifier works on any syntactically plausible input without executing it.

Anatomy of a JavaScript Block

A well-formatted function places the signature and opening brace on one line, each statement indented on its own line, and the closing brace on its own line at the function's depth:

function sum(a, b) {
  const total = a + b;
  return total;
}

How the Beautifier Handles Strings & Regex

JavaScript contains several constructs where characters look like operators but are not: a slash inside a regular expression, a brace inside a template literal, or a semicolon inside a string. The tokenizer treats each of these as a single protected token, so /[{]/g, "a; b", and `${x}` pass through unchanged. This is what separates a safe beautifier from a naive search-and-replace, which would happily re-indent the inside of a string and corrupt it.

Beautify vs Minify

Beautifying and minifying are opposites. The JavaScript Minifier strips every dispensable character for the smallest file size, while the beautifier re-adds readable formatting for development and review. A healthy workflow keeps a readable source file under version control, minifies a copy for production, and beautifies third-party JS when you need to inspect it. The same pattern applies to markup with the HTML Beautifier, to stylesheets with the CSS Beautifier, and to data with the JSON Beautifier.

Common JavaScript Formatting Issues & How to Fix Them

• Indentation looks wrong after a missing brace: if a block is never closed, every following line is treated as one level too deep. Close all open braces and re-run the formatter.
• String contents look mangled: this tool protects quoted strings and template literals, so that should not happen. If it does, your input likely has an unterminated quote — fix the string literal and beautify again.
• Regex detected as a comment or division: a slash is ambiguous. The tokenizer decides based on the previous token, so an unusual expression may confuse it. Add clarifying parentheses or spaces around the regex in your source.
• Everything on one line: if the input has no braces or semicolons (relying on ASI), the beautifier has few places to break. Add braces to control flow or terminate statements explicitly for clearer output.
• Comments shifted onto their own line: line and block comments are preserved and placed on their own indented line so they never collide with code.

Related Tools

Pair this formatter with its counterpart and the rest of our formatting and compression utilities:

• JavaScript Minifier — compress readable JS into the smallest possible output.
• HTML Beautifier — pretty-print minified HTML for review and debugging.
• CSS Beautifier — format stylesheets with nested indentation.
• JSON Beautifier — format and validate JSON with proper indentation.
• HTML Tryit Editor — test your HTML, CSS, and JavaScript live in the browser.