Regex Tester Tool
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About Regex Tester
Test regular expressions against sample strings in the browser. See matches, groups, and flags without deploying code—helpful when debugging validators, log parsers, and rewrite rules.
How to Use Regex Tester
Enter your regex pattern in the pattern field. Paste the test string in the input area. Toggle flags (global, case-insensitive, multiline) as needed. Review match highlights and captured groups, then refine the pattern.
When to Use Regex Tester
Form validation: Prototype email, phone, and slug patterns before shipping. Data cleaning: Extract IDs or dates from semi-structured logs. SEO redirects: Test path patterns before adding server rules. Interviews & learning: Experiment with quantifiers and lookaheads safely.
Why Use This Regex Tester?
Regex errors often surface only on edge-case production data. A live tester shortens the feedback loop compared to redeploying backend validators.
How to use
1. Enter your regex pattern in the pattern field.
2. Paste the test string in the input area.
3. Toggle flags (global, case-insensitive, multiline) as needed.
4. Review match highlights and captured groups, then refine the pattern.
Frequently asked questions
Which regex flavor does this use?
JavaScript RegExp semantics (ES2018+ features where supported by your browser). Server engines like PCRE may differ slightly—re-test before production.