How to use Regex Tester
Enter a regular expression and flags, paste test text, then inspect matches or preview replacement output.
What the tool does
Test a regular expression against sample text, inspect matches and preview replacement output with common JavaScript flags.
Supported inputs
A JavaScript regular expression, optional flags, sample text and replacement text when testing replacements.
Actual output
Matched text and match details, with replacement output when a replacement is supplied.
Privacy and processing
Processing runs locally unless the tool clearly requests a public network resource.
Limitations
Complex expressions can be slow in any browser. Avoid testing untrusted patterns against extremely large text.
Common mistakes
Confirm the JavaScript regex flavour and flags, escape literal special characters, and test edge cases instead of relying on one sample string.
Frequently asked questions
What can I use Regex Tester for?
Test a regular expression against sample text, inspect matches and preview replacement output with common JavaScript flags.
What input does Regex Tester accept?
A JavaScript regular expression, optional flags, sample text and replacement text when testing replacements.
What should I check after using Regex Tester?
Complex expressions can be slow in any browser. Avoid testing untrusted patterns against extremely large text.
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