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Code & Data

Regex tester

Test a JavaScript regular expression: matches, groups, named groups, a replace preview and a time limit against runaway patterns.

  1. 1Fill in the values
  2. 2Click Run
  3. 3See results instantly

Limits

  • JavaScript (ECMAScript) flavour only: PCRE, Python or .NET features such as possessive quantifiers or inline (?i) groups are not available.
  • Runs in a separate worker and is stopped after 2 seconds with a message (catastrophic backtracking protection).
  • Limits: pattern 1,000 characters, text 1 MB, 10,000 matches.

Ask the AI chat

The AI chat can run this tool for you. Try:

  • “test a regex”
  • “regex tester”
  • “check my regular expression”

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