About the Regex Tester
Regex Tester is a free browser-based developer tool from Convertify. Write a regular expression and test it against sample text instantly, with every match highlighted and capture groups listed. Everything runs instantly with no file upload, no account, and no usage limit.
Frequently Asked Questions
Which regex flavor does this use?
JavaScript's native RegExp engine — the same one running in your browser's console. Patterns generally match PCRE/Perl-style syntax, but a few advanced features differ from PHP/Python/.NET regex.
Why is the "g" (global) flag always applied?
Highlighting every match in the text requires scanning the whole string rather than stopping at the first match, so the global flag is always added internally even if you leave it off — your other flags (i, m, s, u, y) are respected exactly as typed.
How do I see capture groups from my matches?
Add parentheses to your pattern to create capture groups — each match's group values are listed below the highlighted text automatically.
Is my pattern or test text sent to a server?
No — matching runs entirely in your browser using JavaScript's built-in regular expression engine.
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