What is a regex tester used for?

It helps you test a regular expression against sample text and see which strings match.

Why does my regex only find one match?

You may need the global flag g, depending on the pattern and runtime.

Can regex parse HTML or JSON reliably?

For complex structured data, use a proper parser. Regex is better for simpler patterns and text checks.

Regex Tester - Test Regular Expressions Online

Regex Tester

Test a regular expression against sample text before using it in code, forms, cleanup scripts, redirects, or validation rules. This tool helps you see matches quickly and adjust the pattern safely.

Regular expression

Flags

Test text

Best use cases

Test email, URL, SKU, ID, or formatting patterns.
Debug cleanup rules before using them in code.
Check whether a pattern is too broad or too strict.

Common mistakes

Forgetting flags such as g for multiple matches or i for case-insensitive matching.
Using a pattern that works on one example but fails on real-world text.
Using regex for complex parsing where a proper parser is safer.

Regex Tester – Test Regular Expressions Online

Regex Tester

Best use cases

Common mistakes

Related tools