Test pattern logic
Regex Tester
Check a pattern, toggle flags, and inspect matches and groups against sample text without opening a full IDE.
- Pattern, flags, and test text in one place
- Returns match positions and groups
- Handles invalid regex syntax with readable errors
Regex Tester
JSON at 26
Groups: JSON
JWT at 39
Groups: JWT
How to use
Step 1
Enter the pattern and flags
Define the expression you want to test and set the matching flags that reflect your real use case.
Step 2
Paste the test string
Use realistic sample text so you can inspect what the regex captures instead of testing on a minimal toy input.
Step 3
Review matches and captured groups
The result shows each match position and any groups, which is helpful when refining extraction logic.
FAQ
Which flags are supported?
The tester uses the JavaScript RegExp engine, so common flags such as g, i, m, s, u, and y are supported.
What happens if the pattern is invalid?
The tester returns the JavaScript regex error message instead of failing silently.
Does it show capturing groups?
Yes. Each match includes captured group values when the expression defines them.
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