What is Regex Tester?
Regex Tester lets you build and debug JavaScript regular expressions interactively. Matches highlight as you type, with group breakdowns and flag toggles.
How to use
- Type a pattern (without the slashes) and toggle flags.
- Paste a test string below.
- Inspect matches and capture groups on the right.
Example
Use this sample to confirm what Regex Tester does before pasting your own data.
pattern: (\w+)@(\w+\.\w+), test: [email protected]
Match: [email protected] | Group 1: support | Group 2: inbrowser.sh
Large inputs are capped and match loops are guarded to reduce browser lockups.
When to use it
Use Regex Tester for quick local checks, debugging, documentation prep, and one-off conversions where opening a full IDE or command-line workflow would be slower. For production-critical data, always review the output before committing or shipping it.
Frequently asked questions
What regex flavor does it use?
JavaScript (ECMAScript) regex via the native RegExp engine.
Is it safe against catastrophic backtracking?
The tester caps input size and guards long match loops to reduce browser lockups, but complex patterns can still be expensive.
Can I share a pattern?
URL sharing is on the roadmap; for now copy/paste both pattern and flags.