What Is an HTML Formatter and Beautifier?
Hand-written or scraped HTML is often inconsistently indented, has attributes in a different order every time, and mixes self-closing and non-self-closing tags. This html formatter online fixes all of that in one paste using Prettier, the same formatting engine that powers countless editor integrations, rather than a fragile regex-based indenter that breaks on real-world markup. Use it as an html beautifier to clean up html markup online, or to format html online and html pretty print it before a code review, and use its html minifier mode to fix messy html code by stripping comments and collapsing whitespace.
How HTML Formatting Works
This is an html formatter with prettier under the hood: your HTML runs through Prettier's dedicated HTML parser rather than a hand-rolled indentation script, so real-world markup, including deeply nested elements and mixed content, formats the way Prettier actually understands it. Minify mode is a separate, lighter pass: it strips HTML comments, collapses whitespace between tags, and removes newlines, then reports the exact byte size before and after and the percentage saved, useful when you want to minify html online free before embedding it in a script or reducing page weight.
Why Whitespace Sensitivity Matters in HTML
Adding a newline and indentation between two inline elements, such as two adjacent span tags, can introduce a visible space in the rendered page that was not there in the original markup, because whitespace between inline elements is significant in HTML rendering. A formatter that does not understand this will silently change how a page looks while claiming to "just" reformat the code. This tool formats with Prettier's htmlWhitespaceSensitivity set to css, which inspects each element's default CSS display value to decide whether surrounding whitespace is significant, preserving visual behavior for inline elements while still reformatting block-level structure freely.
What Minify Mode Actually Does
Concretely, minify removes HTML comments, collapses runs of whitespace between tags into nothing, collapses multiple spaces into one, and strips newlines, then reports the resulting byte size and percentage reduction compared to the original. It does not minify embedded script or style content, rename attributes, or restructure the DOM, it is a whitespace-and-comment minifier, not a full HTML compressor with semantic rewriting.
What This Tool Does Not Do
This tool formats and minifies HTML syntax; it does not validate HTML against the W3C HTML specification, so a document can format cleanly while still using deprecated or invalid tags, and it does not perform a full accessibility audit, though the Detect issues panel flags some common gaps as a courtesy. Formatting requests are processed through a server function using Prettier, since Prettier's HTML plugin is too large to load into every visitor's browser; nothing is stored beyond generating the result.