The pattern runs against bounded input while matches and risk signals remain visible.
11
Data & developer
Regex Tester
Runs a regular expression against sample text and lists match count, positions, and capture groups. Input size is limited to reduce accidental browser freezes.
✓ Free✓ No account✓ In-browser
QUICK ANSWER
What does this tool do?
Test regular expressions with matches and groups.
ResultReady
Your result will appear here.
APPLICATION AND DECISION GUIDE
Regex Tester: method and usage
Runs a regular expression against sample text and lists match count, positions, and capture groups. Input size is limited to reduce accidental browser freezes.
a pattern, flags, and representative matching and non-matching text Confirm the shape first with a small example containing no personal data.
match locations, capture groups, and complexity signals that need review
Practical steps
- Enter sample text.
- Provide the regex pattern and flags.
- Review matches and refine the pattern.
retesting with positive, negative, empty, long, and adversarial boundary cases
A browser match does not guarantee the same result in another runtime; separately test engine compatibility and backtracking cost on adversarial long input.
Suitable use cases
- Validation patterns
- Log parsing
- Search-and-replace preparation
Worked decision record
Match order codes shaped like `ORD-2026-1042` in support text while excluding similar invalid values.
Test `ORD-2026-1042`, `ord-2026-1042`, `ORD-26-1042`, and a very long dash sequence together; keep the pattern and flags visible.
The intended positive sample matches, negative samples do not, positions and capture groups are clear, and the long boundary input does not lock the interface.
If the pattern contains nested unbounded repetition or the target runtime differs from JavaScript, performance-test it in that engine before release.
LEARN THE WORKFLOW
Guides for this tool
Reliable Scheduling with Cron and Unix Time
Prevent time zones, DST, field order, and second-vs-millisecond mistakes from breaking scheduled jobs.
Read guide →How to Combine Code Security Pre-Scans, SAST, and Manual Review
Turn fast regex findings into a sound security workflow with data-flow analysis, dependency checks, SAST, and expert review.
Read guide →QUICK REFERENCE
Open cheat sheet →Regex Cheat Sheet: Patterns, Flags, and Safer Testing
An example-driven reference to JavaScript regular-expression classes, groups, boundaries, quantifiers, and flags.
ABOUT THIS TOOL
Frequently asked questions
What input does Regex Tester accept?+
a pattern, flags, and representative matching and non-matching text Test `ORD-2026-1042`, `ord-2026-1042`, `ORD-26-1042`, and a very long dash sequence together; keep the pattern and flags visible.
What does Regex Tester return?+
match locations, capture groups, and complexity signals that need review The intended positive sample matches, negative samples do not, positions and capture groups are clear, and the long boundary input does not lock the interface.
How should I validate Regex Tester output?+
retesting with positive, negative, empty, long, and adversarial boundary cases If the pattern contains nested unbounded repetition or the target runtime differs from JavaScript, performance-test it in that engine before release.
Does Regex Tester send or store input on a server?+
Tool input is processed in the active tab. Saving to the Workstation or transferring to another tool is a separate choice. Consider browser extensions and shared devices separately; the privacy page explains advertising and network connections.