HTML Formatter

Formatly is a free, fast, and private HTML formatter that beautifies, minifies, and lint-validates your markup entirely in your browser. Paste your code to format HTML online with clean indentation in one click — no data ever leaves your device.

Input

Output

HTML Formatter features

Beautify HTML Instantly

One click re-indents your markup with clean, consistent nesting so deeply structured pages and templates become easy to read.

Powered by js-beautify

Formatting is driven by js-beautify and safely preserves the contents of pre, textarea, script, and style so your inline code stays intact.

Minify HTML

Conservatively collapses whitespace to shrink your HTML for faster page loads, without breaking layout-sensitive markup.

Best-Effort Validation

Lint detects unclosed and mismatched tags and duplicate ids, reporting each issue with its exact line and column.

100% Private & Client-Side

Everything runs in your browser. Your HTML is never uploaded to any server — ideal for proprietary or sensitive markup.

Flexible Indentation

Switch between 2 spaces, 4 spaces, or Tab indentation to match your project's style guide or editor settings.

What is HTML?

HTML (HyperText Markup Language) is the standard markup language for building web pages. It describes the structure of a document using elements written as tags, such as <div>, <p>, and <a>, which the browser renders into headings, paragraphs, links, images, forms, and more.

Each element is typically made of an opening tag, content, and a closing tag — for example <h1>Title</h1>. Some elements are void (self-closing) and have no closing tag, like <br>, <img>, and <input>. Elements can carry attributes such as class, id, href, and src that configure their behavior and styling.

An HTML formatter (or HTML beautifier) re-indents nested tags, normalizes spacing, and puts elements on their own lines so the structure is easy to read and maintain. This is especially helpful for minified production markup, machine-generated output, or large templates where the nesting is hard to follow.

Common uses include cleaning up exported or copied markup, making code-review diffs readable, debugging deeply nested layouts, and preparing HTML snippets for documentation or email templates.

How to format HTML online

Paste your HTML into the editor, or use Upload to load a .html file from your device. No file? Click Sample to load example markup.
Choose your indentation with the Indent control — 2 spaces, 4 spaces, or Tab.
Click Format to beautify the HTML, or Minify to collapse it into a compact single output.
Click Validate to run a best-effort lint that flags unclosed or mismatched tags and duplicate ids with line and column numbers.
Use Copy to copy the result to your clipboard, or Download to save it as a file. Click Clear to start over.

HTML example: before & after

The formatter re-indented each nested element onto its own line using 2-space indentation, while keeping inline elements like b on the same line as their text.

Before

<html><head><title>Hi</title></head><body><div class="box"><p>Hello <b>world</b></p></div></body></html>

After

<html>
  <head>
    <title>Hi</title>
  </head>
  <body>
    <div class="box">
      <p>Hello <b>world</b></p>
    </div>
  </body>
</html>

Formatter vs beautifier vs validator vs minifier

These terms overlap, but each describes a distinct action on your HTML:

HTML Formatter / Beautifier: Re-indents and spaces out your markup so nested elements are readable. "Formatter" and "beautifier" mean the same thing here — Formatly's Format button does this.
HTML Validator: Checks markup for problems. Formatly's Validate is a fast, best-effort lint that catches unclosed/mismatched tags and duplicate ids with line and column — it is not full W3C conformance checking. For strict spec validation, use the W3C Nu Html Checker.
HTML Minifier: Does the opposite of beautifying — it strips and collapses whitespace to make the file as small as possible for production. Formatly's Minify handles this conservatively.

Common HTML errors and how to fix them

Unclosed tag — an element like <div> or <ul> is opened but never closed. Add the matching closing tag (e.g. </div>). Validate reports the line and column of the offending open tag.
Mismatched tags — closing tags appear in the wrong order, e.g. <b><i>text</b></i>. Close elements in the reverse order they were opened: <b><i>text</i></b>.
Missing closing tag on a non-void element such as <p> or <li>. Add the explicit closing tag. Void elements like <br>, <img>, and <input> correctly have no closing tag.
Duplicate id — the same id value is used on more than one element. Make every id unique on the page; use a class for repeated styling or grouping instead.
Unquoted attribute value containing spaces or special characters. Wrap attribute values in quotes, e.g. class="btn primary" instead of class=btn primary.

Private by design

Every byte of HTML you paste is processed locally in your browser. Formatly makes no network request with your data, logs nothing, and stores nothing on any server — so it is safe for API responses, configuration, tokens and other sensitive content. Your most recent input and theme are saved only in your own browser's local storage.

HTML Formatter FAQ

Is the HTML formatter free to use?

Yes. Formatly's HTML formatter is completely free, with no sign-up and no usage limits. You can format, minify, and validate as much HTML as you like.

Is it safe and private to format HTML here?

Yes. Formatting runs 100% client-side in your browser. Your HTML is never uploaded to a server, so it's safe to use with proprietary or sensitive markup.

How do I beautify HTML online?

Paste your markup into the editor, pick an indent size, and click Format. Formatly instantly re-indents and pretty-prints your HTML so it's clean and readable.

What is the difference between formatting and minifying HTML?

Formatting (beautifying) adds indentation and line breaks to make HTML readable, while minifying removes unnecessary whitespace to make the file smaller for production. Formatly offers both with the Format and Minify buttons.

Does the HTML validator check W3C compliance?

No. Formatly's Validate is a fast, best-effort lint that catches unclosed or mismatched tags and duplicate ids with line and column. For full spec conformance, use the official W3C Nu Html Checker.

Does it work offline?

Once the page has loaded in your browser, the core formatting, minifying, and validation run locally without needing a server round-trip, so they keep working even with a flaky connection.

Will formatting break my inline scripts, styles, or preformatted text?

No. Formatting is powered by js-beautify, which safely preserves the contents of <pre>, <textarea>, <script>, and <style> elements so your inline code and whitespace stay intact.