Online Code Beautifier: Make Your JS, CSS, HTML and JSON Readable in One Click
Learn how to beautify and format your JavaScript, CSS, HTML and JSON code instantly. Complete guide to online and editor-integrated beautification tools.
Why beautify your code?
Beautifying (or formatting) code means re-indenting, spacing and structuring a file so it becomes instantly readable. It is the exact opposite of minification: where an online JavaScript minifier compresses your script into a single line, a beautifier expands it back into clean, indented blocks. When you grab a production bundle, a third-party export or a compact API payload, the code is often unreadable — that is when an online JavaScript unminifier or a CSS, HTML, JSON, XML or SVG beautifier becomes essential. FastMinify exposes a Beautify button on every tool: JS, CSS, JSON, HTML, XML and SVG. This guide covers online tools, editor integrations (Prettier, ESLint, EditorConfig), pre-commit hooks, and the right reflexes to stop wasting time on poorly formatted code.
When a beautifier changes everything
You are tracking down an error in Sentry on line 1, column 84327 of an `app.min.js` file. Without a beautifier, you cannot visually locate the block. Paste the file into a beautifier and you get structured, navigable code, ready to be cross-referenced with your source map.
Before optimization
After optimization
Here are the situations where a beautifier saves the most time:
A beautifier re-indents code but does not rename `a`, `b`, `c` variables produced by an aggressive minifier. To go further, combine the beautifier with a source map or a renaming tool. For JS specifically, see our dedicated guide on <a href="/en/blog/how-to-unminify-javascript-debugging" class="text-primary hover:underline">how to unminify JavaScript for debugging</a>.
Editor workflow and pre-commit hooks
Enabling automatic formatting on save kills 90% of style debates in code review. The whole team converges on the same standard with zero effort.
With Husky and lint-staged, every commit automatically beautifies modified files. No PR ever ships pure formatting noise again.
A beautifier is useless if config diverges across machines. Centralize everything in the repo:
Beautify vs Minify: two sides of the same cycle
Beautify formats code for humans; minify compresses it for production. Both operations preserve semantics: a valid file stays valid after each pass. JavaScript example:
Before
function add(a,b){return a+b;}const result=add(1,2);console.log(result);After
function add(a, b) {
return a + b;
}
const result = add(1, 2);
console.log(result);A beautifier works on layout, not logic. Here is the boundary to know:
Beautify in one click with FastMinify
Every FastMinify tool exposes a Beautify button next to Minify. Processing stays 100% client-side: no server upload, perfect for sensitive files or internal payloads.
Pick the tool that matches your language
Use the <a href="/en/minify-js" class="text-primary hover:underline">JavaScript beautifier</a> for JS, the <a href="/en/minify-css" class="text-primary hover:underline">CSS beautifier online</a> for stylesheets, and so on for HTML, JSON, XML and SVG.
Paste the minified code
Drop the content into the left editor. The tool detects the syntax and reports errors before formatting.
Click Beautify
The reformatted code appears instantly on the right. Copy the result or download it to reuse in your IDE.
An online tool covers cases where you do not have access to your stack or a dev environment (customer support, one-shot audit, quick sharing).
Beautify in your editor and your scripts
Prettier is the reference tool. It installs in one command and works on virtually every front-end language. Configure it via `.prettierrc` and turn on Format on Save in VS Code to never think about it again.
Configuration
// .prettierrc
{
"semi": true,
"singleQuote": true,
"trailingComma": "all",
"printWidth": 100,
"tabWidth": 2
}Usage
# Install
npm install --save-dev --save-exact prettier
# Beautify the whole project
npx prettier --write "**/*.{js,ts,css,html,json,md}"
# Check without writing (CI)
npx prettier --check "**/*.{js,ts,css,html,json,md}"ESLint auto-fixes both style AND quality issues (unused variables, unsorted imports). Combine it with Prettier via `eslint-config-prettier` to avoid conflicts.
Configuration
// eslint.config.mjs
export default [
{
rules: {
'indent': ['error', 2],
'quotes': ['error', 'single'],
'semi': ['error', 'always']
}
}
];Usage
# Auto-fix every file
npx eslint . --fix
# Combine with Prettier
npx eslint . --fix && npx prettier --write .To beautify without installing Prettier, native or built-in tools do the job: `JSON.stringify(obj, null, 2)` in Node, `jq '.'` on the command line, `html-beautify` for legacy HTML.
Basic example
// Beautify JSON with native JavaScript
const minified = '{"user":{"name":"Ada","age":36}}';
const pretty = JSON.stringify(JSON.parse(minified), null, 2);
console.log(pretty);Usage
# Beautify JSON with jq
jq '.' minified.json > pretty.json
# Beautify HTML with js-beautify
npx js-beautify --type html input.html -o output.html
# Beautify SVG with xmllint
xmllint --format icon.svg > icon.pretty.svgBeautify per language: concrete examples
Pull a production bundle and get readable code in seconds. Tip: if you are working on minified code without a source map, also check our guide how to unminify JavaScript for debugging.
JavaScript example
function fetchUser(id){return fetch(`/api/users/${id}`).then(r=>r.json()).catch(e=>console.error(e));}Command line
function fetchUser(id) {
return fetch(`/api/users/${id}`)
.then((r) => r.json())
.catch((e) => console.error(e));
}Minified CSS strips every space and merges selectors. A beautifier brings back the structure and makes cascade audits much easier.
JavaScript example
.btn{display:inline-flex;align-items:center;padding:.5rem 1rem;border-radius:.375rem;background:#3b82f6;color:#fff}Command line
.btn {
display: inline-flex;
align-items: center;
padding: 0.5rem 1rem;
border-radius: 0.375rem;
background: #3b82f6;
color: #fff;
}Declarative formats benefit massively from clean indentation. Especially true for Illustrator SVG exports and large XML sitemaps.
Conclusion
Beautifying code is not a luxury: it is the reflex that turns a one-hour debug into five minutes, makes auditing third-party code feasible, and aligns your team on a shared standard. The right workflow combines an online tool for one-shot cases (debugging a prod bundle, reading a client export) with an automated chain — Prettier, ESLint, EditorConfig, pre-commit hooks — for daily projects. Send files back through a minifier when you ship; that is the other side of the same cycle. To go deeper on choosing between online tools and build tools, read our comparison <a href="/en/blog/online-minifiers-vs-build-tools-webpack-vite-terser" class="text-primary hover:underline">online minifiers vs build tools</a>.
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