HTML Syntax Checker

Paste HTML to compare focused source diagnostics with the browser-parsed DOM without sending markup to a server.

HTML source

0Focused issues

0Parsed elements

0Source lines

0Unique IDs

Browser-normalized document

Focused HTML diagnosticsThis is not the full WHATWG parse-error stream; browsers can recover from malformed markup in ways a simple source stack cannot represent.

Use the connected HTML workflow

Format source first, validate or repair deliberately, preview in the right context, inspect the parsed structure, then export only after the final project check.

Browser-local does not mean standards-complete

HTML parsing is error tolerant. Focused diagnostics, sandboxed preview and transformation helpers do not replace full conformance, security or production-browser testing.