HTML Tag Validator
Check HTML for unclosed and mismatched tags, with each problem named.
Quick answer: enter your details below and click Validate Tags — your result appears instantly, right here in your browser. Nothing you enter is uploaded or stored.
H
Converters & Utilities
Enter your details below.
How to use
- Paste the HTML fragment you want to check.
- Click Validate Tags.
- Read each reported problem in order.
- Fix the first mismatch first, then validate again.
About this tool
A single unclosed tag can shift a whole page layout, and the fault is often far from the visible break. This validator walks through your markup with a simple stack, pairing each closing tag with the most recent open one and listing whatever is left over. Void elements such as line breaks and images are allowed to stand alone, so only real imbalances are reported.
Frequently asked questions
Does it check attributes or nesting rules?
No. It checks tag balance only, so a well-balanced but semantically odd page can still pass.
Why are br and img not flagged as unclosed?
They are void elements that never take a closing tag, so the validator lets them stand alone.