HTML Formatter

HTML Formatter is a free online tool that reformats and beautifies HTML code with proper indentation, consistent spacing, and clean structure. Paste any raw, minified, or poorly-formatted HTML and get readable, consistently indented output ready to use in your editor, code review, or documentation. All processing happens in your browser — no server upload required.

Readable HTML is not just an aesthetic preference — it is a practical necessity for maintaining and debugging web pages. Minified HTML compressed to a single line is effectively unreadable to humans. HTML generated by CMS platforms, email builders, and visual editors is often excessively nested, inconsistently indented, and filled with redundant whitespace. HTML scraped from websites arrives in whatever format the source site uses. HTML copied from Word, Google Docs, or design tools carries inline styles, wrapper divs, and structural quirks. Formatting restores visual structure, making it possible to read, understand, and edit the markup efficiently.

Consistent indentation is the foundation of readable HTML. The standard convention is to indent each nested element by 2 or 4 spaces relative to its parent. A div containing a ul containing multiple li elements should be indented at three levels — the div at root, the ul one level in, each li two levels in. When indentation is consistent, the nesting structure is immediately visible. You can see at a glance whether every div is correctly closed, whether elements are at the right nesting level, and where sections begin and end.

HTML Formatter is especially valuable when debugging layout issues. A common cause of unexpected rendering behaviour is incorrectly nested or unclosed elements — a paragraph accidentally inside an anchor tag, a div closed too early or too late, or a table missing its tbody. These errors are invisible in a single-line minified string but immediately obvious in properly indented HTML. Many developers' first debugging step when facing unexpected layout behaviour is to format the rendered HTML to see the actual structure before inspecting CSS.

Email HTML is a particularly important use case. Email templates use table-based layouts for Outlook compatibility, inline CSS, and deeply nested conditional comments. HTML generated by builders like Mailchimp, HubSpot, and Klaviyo is minified and completely unreadable. Formatting the HTML makes it possible to understand the structure, find the specific section to edit, and make targeted changes without accidentally breaking surrounding code. Even small email template edits require readable HTML to be done safely.

Frontend developers use HTML Formatter to inspect components generated by frameworks and server-side rendering engines. Template outputs in Django, Jinja2, ERB, Blade, and similar systems can produce inconsistently spaced HTML depending on template whitespace handling. Code review of HTML changes is dramatically more effective when both the original and modified files are formatted consistently — reviewers can focus on meaningful changes rather than whitespace noise. Documentation HTML is formatted before inclusion in wikis and README files.

HTML Formatter works entirely in your browser using a JavaScript HTML parsing and serialisation approach. The input is parsed into a document structure, then serialised with consistent indentation applied at each nesting level. Self-closing tags, void elements (br, hr, img, input), and inline vs block element distinctions are handled correctly. Formatting does not modify the rendered visual output of the HTML — browsers render it identically. No data is sent to any server.