JavaScript Formatter

Format JavaScript and JSX with Prettier — the same engine your editor uses, with no install.

Code FormattersRuns in your browserFree, no sign-up

Options

Indentation

Semicolons

Single quotes

Line width

The column Prettier tries to wrap at. Not a hard maximum.

JavaScript input

Formatted JavaScript

Output appears here as you type.

Ctrl + Enter to run

About the JavaScript Formatter

Formatting parses to a syntax tree and prints it back, so the program is preserved by construction and only its layout changes. Consistent layout is what makes a diff show the change you made rather than a reflow of everything around it.

It runs Prettier itself, not a reimplementation, so the output matches your editor. The main use is code you did not write — a vendor snippet, a bundled file, something pasted from an issue thread — where restoring structure is the difference between reading it and guessing at it.

Frequently asked questions

Which JavaScript syntax is supported?

Everything Prettier's Babel parser accepts: ES2024, JSX, optional chaining, top-level await, decorators, class fields and private methods. TypeScript-specific syntax such as type annotations and interfaces is not — that needs the TypeScript parser.

Is this the same as Prettier in my editor?

Yes, it is Prettier's standalone build running in your browser, so the output matches your editor for the same options. The one difference is that this page cannot read your project's .prettierrc, so set the options above to match it.

Can it recover minified code?

It can re-indent minified JavaScript and make it readable, but it cannot restore what the minifier deleted. Variable names mangled to a, b, c stay mangled, and dead code that was eliminated is gone. For that you need a source map.