HTML Formatter

Prettify and indent messy or minified HTML. Paste your markup and get back clean, consistently indented output ready to read or edit.

By Pankaj Kumar · DevToolsHub · Last updated Jun 2026

How the formatter processes your markup

Click Format and the input is sent to the DevToolsHub API (limit: 1 MB), where a regex pass wraps every <tag>-shaped fragment in newlines, then splits and indents based on a depth counter that increments on opening tags and decrements on closing ones. Void elements like <br>, <img>, <input>, and <link> are tracked in a fixed set so they don't increment the depth — the 14 HTML5 void elements are hardcoded, and the depth counter also guards against going below zero on mismatched closing tags rather than throwing.

It's pattern-based rather than a true HTML parser — there's no DOM tree built behind the scenes. The practical consequence beyond the existing <script> limitation: every tag gets its own line, including inline elements. <p>Hello <strong>World</strong>!</p> becomes five lines (opening p, text "Hello", strong, text "World", closing strong, "!", closing p), which is valid HTML but unusual and can make inline content unexpectedly verbose after formatting. For purely block-level HTML this is invisible; for mixed inline/block layouts it produces more lines than a DOM-aware formatter would.

Why HTML gets messy

HTML reaches a state that needs formatting from several common sources. Build tools, template engines, and server-side frameworks often output HTML as a single continuous line to save bandwidth. When developers copy markup from browser DevTools or design tools like Figma, the indentation rarely matches the target codebase. Auto-generated HTML from email builders, CMS platforms, and static site generators follows their own internal formatting rules. Code that has been edited many times by different developers accumulates inconsistent indentation. In all these cases, a formatter restores readability without requiring manual line-by-line editing.

HTML document structure

Well-formatted HTML follows a clear hierarchy. The <html> element contains <head> and <body>. Block-level elements like <div>, <section>, <article>, <header>, and <footer> are indented one level relative to their parent. Inline elements like <span>, <a>, <strong>, and <em> sit within block-level elements without extra line breaks. Self-closing void elements like <img>, <input>, <br>, and <hr> appear on their own line within their parent.

Semantic HTML5 elements

HTML5 introduced semantic elements that carry meaning about the content they contain, helping search engines and screen readers understand page structure. Well-formatted HTML makes these elements visible and their nesting clear:

  • <header> — introductory content or navigation for the page or a section
  • <nav> — a block of navigation links
  • <main> — the primary content of the page (use once per page)
  • <article> — self-contained content that could stand alone (blog post, news item)
  • <section> — a thematic grouping of content
  • <aside> — content tangentially related to the main content (sidebar, callout)
  • <footer> — footer content for the page or a section

How to use this tool

  1. Paste your HTML — minified, copied from DevTools, or just inconsistently indented — into the input editor.
  2. Click Format.
  3. Review the indented output on the right.
  4. Copy and paste back into your editor or project file.

Formatter vs Minifier

This tool is the direct counterpart of the HTML Minifier. Use the formatter to make HTML readable for editing, code review, or debugging. Use the minifier to produce lean, small output for production deployment where file size matters. Keep formatted source in version control and minify as part of your build pipeline, so you always have readable source to return to.

Note that the HTML Minifier on this site has a known limitation (documented on that page): its first regex pass removes all whitespace between adjacent inline elements, which can concatenate words that were previously separated by a space. Formatting then re-minifying the same HTML through both tools doesn't guarantee a round-trip to identical output for mixed inline/block content.

This tool is built with ASP.NET Core 8, Blazor Server, and a custom regex-based indentation engine. It runs securely on Microsoft Azure.
FAQ
What is the difference between a formatter and a minifier?

A formatter adds whitespace and indentation to make HTML readable. A minifier removes whitespace to reduce file size. Both produce functionally identical HTML.

Will formatting break my page layout?

No. Browsers ignore insignificant whitespace between block-level elements. The formatted HTML renders identically to the original.

Does it handle inline elements like <span> and <strong>?

Inline elements are placed on their own line within their parent's indented block. This keeps output consistent and readable.

Does it format embedded CSS or JavaScript?

Embedded <style> and <script> content is indented as a block but the code inside is not reformatted. Use a dedicated CSS or JS formatter for those.

What indentation does it use?

Two spaces per level, which is the most widely used convention for HTML.

Can I use this with template engines like Jinja or Handlebars?

Yes, as long as the template syntax does not break basic HTML tag structure. Template expressions inside attribute values are preserved.

Related Tools
Input Section

HTML input

Output Section

Formatted output

HTML result

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