Processed locally in your browser.Normal formatting and conversion do not send source text to the server.
Input HTML
Output HTML
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Developer Tools · Runs locally in your browserMore Developer Tools
What is HTML Validator?
HTML Validator is a focused developer workspace that helps you check whether HTML can be parsed and surface structural warnings. It uses established parsers and compilers instead of brittle regular-expression transformations. Normal input remains in the browser, and the page shares RankSmartTools navigation, theme, access controls, search, metadata and download behavior.
Check whether HTML can be parsed and surface structural warnings. This makes it useful for API responses, configuration files, test fixtures and data exchanged between development systems.
How to use HTML Validator
- Paste source text or load a compatible local file.
- Choose the primary action and review any parser diagnostics.
- Inspect, copy or download the generated output.
- Clear sensitive content when finished; browser memory is opt-in.
Features
- Local-first processing and Unicode-safe text handling
- Parser-aware transformations with actionable errors
- Keyboard-friendly responsive editor with dark-mode support
- Copy, download, file-drop and optional input memory
Example HTML input
<main><h1>RankSmartTools</h1><p>Local-first developer utilities.</p></main>Frequently asked questions
No. Formatting and conversion parse text but do not run submitted scripts or commands.
Normal operations run locally in the browser. Remote URL loading is clearly identified as a server operation where available.
Equivalent data structures are preserved where the formats overlap. The output and page notes identify transformations that cannot represent format-specific features exactly.