Regex tester
Test a regular expression against sample text and review matches instantly.
Input
Result
Inputs are processed in your browser and are not sent to the server. Privacy by design
How to use
- Test regular expressions against sample text for validation rules, log parsing, search patterns, and quick debugging.
- Paste or type only sample data that is safe to inspect.
- Review the result before copying it into code, docs, or tickets.
How it works
The pattern is evaluated against your sample text in the browser. This page uses a timeout-oriented approach to reduce the risk of runaway expressions.
Examples
- Check whether an email-like pattern matches test strings.
- Debug a log line capture group before using it in code.
- Compare greedy and non-greedy matches on a short sample.
FAQ
Can regex be slow?
Yes. Some patterns can be expensive, so keep samples small.
Does it replace a full test suite?
No, use it for quick exploration only.
Why is my match different?
Flags, anchors, and escaping rules can change behavior.
Can I paste logs with secrets?
Avoid secrets and private production logs.
Pattern checks
Keep the sample text small and representative, then test anchors, flags, groups, and escaping one change at a time. This makes it easier to see whether the match changed because of the pattern itself or because the input contains a newline, extra space, or unexpected punctuation. Important production patterns should still be verified in the target runtime.
Review workflow
Start with a short sample that contains one expected match, one expected non-match, and one edge case. Adjust anchors, groups, escaping, and flags one at a time so the result is easy to explain later. For log parsing, include only sanitized lines and avoid production secrets. For validation rules, remember that a passing regex test is not the same as full business validation. After the pattern looks right here, run it in the target language or framework because regex engines can differ.
Security and limits
Regular expressions can behave differently across engines, so verify important patterns in the target runtime.
Safe execution
Regex tests run in an isolated worker and stop automatically after 2 seconds to protect the page.