regex101: privacy-focused regex testing
Build, test, and debug regular expressions locally in your browser. Test strings and files stay on your device during processing.
Test PCRE2, JavaScript, Python, Go, Java, .NET, Rust, and POSIX patterns in regex101. Inspect explanations and capture groups, replace text, and keep expected results in unit tests.
Worked examples
Verify an AI-generated regex
Test accepted and rejected inputs before using a generated pattern in your application.
Extract fields from logs
Extract order IDs, add regression tests, and run the generated JavaScript.
Clean text in steps
Load a file, apply two replacement layers, and copy the completed text.
Compare regex performance
Compare execution times for the same inputs and repeat the measurement in Node.js.
regex101 Pro
Pro supports more than two test strings, substitution pipelines, benchmarks, and document extraction.
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