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Free Online Regex Tester

Test a JavaScript regular expression in a time-limited worker.

Your input stays on this device. Processing is bounded; regex runs in a worker with a two-second timeout.

Result



How to use Regex Tester
Test a JavaScript regular expression in a time-limited worker. JavaScript regex syntax is used. Browser execution is isolated in a worker and stopped after two seconds. Inputs are limited to 20,000 characters and patterns to 2,000; at most 1,000 matches are shown.
  1. Set Input.
  2. Set Regular expression.
  3. Set Flags.
  4. Run the tool, review the result and its stated limitations, then copy or download if needed.
Example & practical use
Test a JavaScript regular expression in a time-limited worker. The example below demonstrates Input; Regular expression; Flags.
Example input:
{
  "text": "abc 12 def",
  "pattern": "\\d+",
  "flags": "g"
}
Expected result (relevant fields):
[
  {
    "match": "12",
    "index": 4,
    "groups": []
  }
]
Features & result limitations
JavaScript regex syntax is used. Browser execution is isolated in a worker and stopped after two seconds. Inputs are limited to 20,000 characters and patterns to 2,000; at most 1,000 matches are shown.
Frequently asked questions
What inputs does Regex Tester accept?
Input; Regular expression; Flags
How should I interpret the Regex Tester result?
JavaScript regex syntax is used. Browser execution is isolated in a worker and stopped after two seconds. Inputs are limited to 20,000 characters and patterns to 2,000; at most 1,000 matches are shown.
Where does Regex Tester process my data?
Inputs are processed locally in your browser. Submitted text is not sent to external services. A successful-run event increments an aggregate tool counter without your input.