The free online JavaScript beautifier reformats minified or messy code into readable, indented lines, with a choice of indent size and brace style. Because it runs in the browser, the code is never uploaded.
Developer tools by OnlinePCApps since 2013
Minified or cramped JavaScript is a wall of code no one can follow. The free online beautifier re-spaces it into clean, indented lines, so the logic is there to read, debug and review.
A production bundle or an inline script is packed onto one long line to save bytes. Beautifying spreads it back across indented lines, so the flow of a function can be followed and a bug tracked down.
Code pasted from a console, a doc or an answer online often lands with ragged indentation and stray spacing. One pass gives it consistent indentation and spacing before it goes into a project or an article.
A tracking snippet or an embed arrives minified, and it is hard to trust code that cannot be read. Beautifying lays it out so what the script actually does can be checked before it goes on a page.
Paste the JavaScript into the panel above, or drop a .js file. A minified bundle, a cramped snippet or a block of JSON, CSS or HTML all work as input, read on the device.
Choose the indent size and character, two spaces or a tab. Then set the brace style, braces attached in the K&R way or dropped to their own line in the Allman way. The output reflows as each setting changes.
Copy the formatted code, or download it as a file. The input stays untouched, so the same code can be reformatted with a different indent or brace style at any time.
To beautify code is to re-space and re-indent it without touching what it does. The tool does that on the device.
The code is scanned for braces, brackets, parentheses and semicolons, then laid out with a newline after each opening brace and statement and an indent for each block. A function crammed onto one line becomes a properly nested, readable block.
The indent can be two or four spaces, or a tab, set to match a project or a personal habit. Existing blank lines can be kept or trimmed, so the spacing lands the way the reader expects rather than the way the input happened to arrive.
A brace can sit on the same line as its statement in the K&R way, or drop to its own line in the Allman way. Choosing a brace style rewrites the layout to that convention across the whole file in one pass.
The same beautifier handles JSON, CSS and HTML, not JavaScript alone. A block of any of the four is re-indented and spaced to its own rules, so one tool tidies the mixed files a front-end project tends to hold.
To beautify JavaScript, to format JS and to un-minify a script all name the same tool. A search for JS beautifier or JavaScript formatter reaches this page, and the input code is left as it is.
Beautifying re-spaces the code without changing it. These points decide how the output reads.
| The case | Result | What happens and why |
|---|---|---|
| Languages | JS, JSON, CSS, HTML | JavaScript, JSON, CSS and HTML are each re-indented to their rules. |
| Indent | size and char | Two or four spaces, or a tab, set to match a project or a habit. |
| Brace style | K&R or Allman | Braces attached to the statement, or dropped to their own line. |
| Logic | untouched | Only whitespace changes, so the code runs exactly as before. |
| Strings | preserved | Quotes and template literals are kept exactly as written. |
| Comments | kept | Beautifying leaves comments in place, unlike a minifier. |
| Mangled names | not restored | Structure returns, but names a minifier shortened stay short. |
| Minify | the reverse | Beautify adds whitespace to read, minify strips it to shrink. |
| Where it runs | on the device | The code is formatted in the browser, so nothing is uploaded. |
How a Beautifier Reformats Code
A beautifier works purely on the shape of the code, never its meaning. It scans the text for the structural marks, the braces, brackets, parentheses, semicolons and string literals, then rebuilds the layout around them, adding a newline after each opening brace and each statement, raising the indent inside a block and lowering it at the close. A function squeezed onto one line comes back as a properly nested, readable block. The important part is what it does not do. Not a single token is added, removed or reordered, so the beautified code runs exactly as the input did. A branch is never rewritten into a different shape. String and template literals are copied across untouched, and comments are left in place, unlike a minifier that would strip them. That last point sets the honest limit. Beautifying restores the structure of minified code but cannot restore what a minifier truly removed, so variable names that were shortened to single letters stay short and comments already stripped do not return. Choosing a brace style, attached in the K and R way or on its own line in the Allman way, together with an indent size then rewrites the layout to that convention. The references below cover the tools.
Both format code. The split is a quick configurable one-off against an opinionated project formatter.
| Point of comparison | This tool Formatted in the browser On the device | Prettier Uploaded to a formatting service |
|---|---|---|
| Where the code goes | Formatted in the browser | Runs on the machine |
| Price and caps | Free with no file cap | Free tier often capped |
| Pick the brace style | K&R or Allman, either way | One opinionated style |
| Format a whole project | One file or snippet | Every file on save |
| Read a minified file | Paste and read at once | Set up in a project first |
Prettier wins for a whole project held to one agreed style on every save, with no bickering over layout. This beautifier wins for a quick one-off, a minified file to read or a snippet to tidy, with a brace style of choice and nothing to set up. Both run on the machine.
The code is parsed and reformatted inside the browser, so the work is client-side and it stays on the machine that opened it. No copy is passed to a server for the job.
Source code is often proprietary, an unreleased feature or a private key hiding in a config, none of it meant for an outside server. A hosted formatter has to upload the whole file to lay it out, far more exposure than a reindent is worth.
Each of these lays code out cleanly. They differ in setup, in how much they decide for the writer and where the code goes.
An editor, the command line, a linter and an IDE all format code, yet each means a setup, a project or a terminal. This page beautifies a pasted block or a file at once, with a brace style of choice, kept local with nothing to set up.
A little context sets a cleaner result.
Beautifying adds and removes spacing and line breaks alone. No token is added, removed or reordered, so the code runs exactly as it did before. A branch or a loop keeps the same shape, only laid out to read.
Beautifying restores the structure of minified code but not what a minifier truly stripped. A variable renamed to a single letter stays that way, and comments already removed do not come back, since neither was in the file to recover.
Set the brace style before the pass, since it shapes the whole layout. Attached K&R braces keep a file compact, while Allman braces on their own line suit a codebase that reads them that way. Match whatever the project uses.
The browser formats one file or a pasted block, which fits the code in hand. A whole repository held to one style on every save, or a check that gates each commit, belongs on a formatter such as Prettier wired into the editor and the build, which reads from disk across the project.
A formatter in the editor lays out each file the moment it is saved, so the whole project stays to one style without a manual pass.
A check runs before each commit and refuses code that is not formatted, so a shared style is kept without anyone policing it by hand.
A single style config sits in the repository, so every developer and the build format the code the same way, with no per-person setup.
Free and online, with no sign-up and no upload. Format minified or messy JavaScript in the browser, all on the device.