Regex Tester
DeveloperTest regular expressions against any text with live highlighting and a match counter. Supports the g, i, m, s and u flags; 100% client-side.
Testing runs entirely in your browser as you type.
What is a Regex Tester?
A Regex Tester applies a regular expression to your text and shows the result live while you type. Matched pieces are highlighted, a match counter updates on every keystroke, and invalid patterns explain their error instead of failing silently.
Which flags are supported?
- g — global: find all matches instead of just the first.
- i — ignore case: a matches both a and A.
- m — multiline: ^ and $ match line starts and ends.
- s — dot-all: . also matches newline characters.
- u — unicode: enables unicode-aware escapes such as \p{...}.
How do I anchor my pattern?
Use ^ to anchor to the start of the text and $ to the end. Without anchors a pattern matches anywhere in the text. Add \b word boundaries for whole-word matching and use parentheses to capture groups you want to reuse.
Is my data safe?
Yes. Matching runs entirely on your device; your pattern and test text never leave the browser. Log lines, tokens or code samples can be tested here safely.
Frequently Asked Questions
What is Regex Tester?
Tests a regular expression against your text live and highlights every match.
How do I use Regex Tester?
Type or paste your data into the field on this page and press the button. The result is calculated instantly in your browser — nothing is uploaded.
Is Regex Tester free?
Yes, Regex Tester is completely free. No signup, no downloads and no usage limits.
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