Regex library
Regular expression for HTML tags
A teaching regex that finds opening and closing HTML tags. Not an HTML parser — use it to highlight, not to sanitize.
<\/?[A-Za-z][A-Za-z0-9]*(?:\s[^<>]*)?>
Runs 100% in your browser. Nothing you paste is uploaded, stored, or sent to a server.
Highlighted matches
How to use
- Scan the pre-filled pattern and the sample. Hits are highlighted; misses stay plain.
- Toggle flags if you need global or case-insensitive matching. The pattern is JavaScript / ECMAScript.
- Paste your own corpus. Nothing is sent to a server.
- Read the notes below before you drop the pattern into production — several of these are intentionally incomplete.
You cannot parse HTML with a regex in the general case. You can still find tag-shaped spans in a snippet, which is useful when you want to highlight markup in a small demo.
Do not use this to sanitize user HTML. A tag regex will miss comments, CDATA, SVG, and malformed markup that still executes in a browser.
What this pattern will not do
The g flag is on so every tag in the sample is listed.
Script contents are not parsed; only the <script> and </script> tokens match.
FAQ
Can I strip tags with this?
Not safely. Use a real sanitizer (DOMParser plus an allow-list, or a dedicated library) for untrusted HTML.
Why is this still useful?
For teaching, for linting known-good snippets, and for counting tags in a fixture.
Is the sample text uploaded?
No. The tester compiles the pattern with the browser’s RegExp engine and stays on the device.