Before you start
What you need
A JavaScript-compatible pattern, optional flags, and bounded text created for testing.
Developer & Data
Regex Tester
Run a bounded JavaScript regular expression against test text and inspect match positions and groups.
- 01Runs in this browser
- 02Limits are explicit
- 03Copy or download output
No black box
How this tool handles the input
A JavaScript RegExp is created after flag validation. Global matching is added for complete reporting, with indexed and named groups returned.
What you get
What the page gives back
A JSON match report with positions, groups, count, and truncation status.
Keep in mind
Use the result responsibly
Pathological expressions can be expensive even on short text. Do not use this page to test untrusted production patterns.
Practical uses
Where this tool earns its place
- Check capture groups before coding.
- Test a log-line pattern against samples.
- Inspect named-group output positions.
Verified data boundary
Source text stays on this page.
The published contract marks these tools as client-only processing. Nirmion uses the API only to confirm that this workspace is enabled in MySQL; source values and results are not sent to Flask.