Regex Tester
Test regular expressions with live matches.
How to use the Regex Tester
Paste your input
Drop the snippet, token or document into the editor. Invalid characters are highlighted as soon as parsing fails.
Choose how to process it
Select formatting, validation or conversion options. Results are calculated as you type, with no submission step.
Copy or download
Use the copy button for a clean result, or download it when the output is large.
What Regex Tester is for
Build a pattern, choose flags and see matches, groups and capture indexes as you type. A cheat sheet covers the syntax most people forget.
The Regex Tester is part of the Developer collection on ToolFlow. It is designed for one concrete job: test regular expressions with live matches. Everything runs client-side, so you can use it with sensitive material without creating a copy on someone else's server.
Common use cases
- Validate an input mask
- Extract fields from logs
- Debug a greedy pattern
Good to know
- No account is required, and there is no usage limit on the browser tool.
- Processing happens locally. Files are read from disk and the result is written back to your downloads folder.
- Results are reproducible: the same input and options produce the same output, with no hidden server round-trip.
- If the tool needs a live data source, the page states it explicitly instead of silently failing.
Regex Tester FAQ
The questions people ask before using this tool.