JS Pretty Print
JS Pretty Print transforms minified, bundled, or poorly formatted JavaScript into clean, consistently indented code that you can actually read and debug. We built six JavaScript utilities into one workspace so you can pretty print, compact, syntax check, analyze structure, evaluate expressions, and match brackets without leaving the page. Paste your JavaScript into the editor on the left, upload a .js file from your computer, or drag and drop it onto the workspace. All processing happens locally in your browser, so your source code never leaves your device.
JS Pretty Print
Formats minified or messy JavaScript into clean, indented code. Configure indent size, brace placement, and blank lines between functions. Uses the js-beautify library for accurate ES6+ formatting.
JS Compact
Removes all comments and collapses whitespace from JavaScript to produce the smallest possible single-line output for production deployment.
JS Syntax Check
Validates JavaScript syntax using the browser native engine. Reports valid status with line and function counts, or the exact error message for invalid code.
JS Stats
Produces a comprehensive code report covering lines, functions, variables, control flow statements, module imports and exports, and string literal counts.
JS Safe Eval
Evaluates JavaScript expressions in strict mode isolation. Useful for quick math, string operations, array transforms, and JSON formatting without opening a console.
Bracket Matcher
Scans JavaScript for unmatched parentheses, square brackets, and curly braces. Understands strings and comments so quoted brackets are correctly ignored.
Free JS Pretty Print with Configurable Formatting
Minified or machine-generated JavaScript is nearly impossible to read. Variable names compress into single characters, function bodies collapse onto single lines, and nested callbacks become unnavigable walls of text. The free JS Pretty Print tool on this page takes any JavaScript input and expands it into a clean, consistently indented structure. Each statement appears on its own line with your chosen indent width. Function bodies, object literals, and array expressions are properly nested. The tool includes three configurable options: indent size (2 spaces, 4 spaces, or tab), brace placement (same line or new line using Allman style), and blank lines between top-level function blocks for visual separation.
How the Pretty Printer Works
The formatter uses the js-beautify library, loaded from a public CDN, to parse and reformat your JavaScript. js-beautify understands modern JavaScript syntax including arrow functions, destructuring assignments, template literals, async/await, class declarations, optional chaining, and ES module syntax. It preserves the logical structure of your code while adding consistent whitespace and newlines to make it readable. The output updates automatically as you type, so you see the formatted result in real time.
When to Pretty Print JavaScript
Production bundles from webpack, Rollup, or esbuild compress JavaScript into a single line for performance. When you need to debug a production issue, inspect a third-party library, or review unfamiliar code, pretty printing is the first step. API responses that include inline scripts, browser extension code, and copy-pasted snippets from documentation all benefit from reformatting before review.
Online JS Pretty Print with Compact and Syntax Tools
Beyond formatting, this page includes complementary JavaScript utilities that work together in a typical development workflow. Start by pretty printing minified code to make it readable. Edit and debug. Then use JS Compact to strip it back to the smallest possible output for production. Run JS Syntax Check to catch missing brackets, unclosed strings, and unexpected tokens before deployment. Use JS Stats to measure code complexity by counting functions, variables, control flow statements, and module dependencies. JS Safe Eval lets you test quick expressions without opening a browser console. And Bracket Matcher catches mismatched parentheses and braces that cause hard-to-find runtime errors.
JS Compact for Production
The JS Compact tool performs the inverse of pretty printing. It removes all single-line comments, block comments, and excess whitespace, then joins the result onto a single line. The output is code that JavaScript engines parse identically to the original but with the smallest possible byte count. Use it after editing to prepare scripts for deployment when you do not have a build tool available.
JS Syntax Check Before Deployment
The syntax checker uses the browser built-in JavaScript engine to validate your code. If the code parses successfully, you see a green confirmation with line count, character count, and function counts. If there is a syntax error, the exact error message from the engine is displayed so you can jump to the problem line and fix it immediately.
Your JavaScript Stays Private in Your Browser
We process everything locally using JavaScript APIs in your browser. No server requests, no cookies, no account required. You can safely pretty print production scripts containing API keys, internal logic, and proprietary algorithms knowing that nothing is transmitted anywhere. The js-beautify library is loaded once from a public CDN and all subsequent processing runs completely offline.
Related Online JavaScript and Code Tools
If you work with JavaScript regularly, these free tools complement what you can do here:
- JS Formatter -- format, minify, validate, escape, convert, and analyze JavaScript in one tool
- JavaScript Validator -- validate JavaScript syntax and check for errors
- Code Formatter -- format JavaScript, HTML, CSS, JSON, and more in one workspace
- JSON Formatter -- format, minify, validate, and transform JSON data
- CSS Pretty Print -- pretty print, compact, autoprefix, and lint CSS
- HTML Beautifier -- beautify and format HTML with syntax highlighting
- Base64 Decoder -- decode Base64-encoded strings and files