Regular Expression Tester
Debug regular expressions with real-time execution, capture group analysis, replacer previews, split testing, and pattern breakdowns across all JavaScript regex features.
How It Works
Write or Paste Your Pattern
Enter regex syntax with optional flags. The editor supports syntax highlighting, flag toggles, and instant validation for malformed expressions.
Add Test Data & Choose Mode
Paste sample text, enable multi-input testing, and switch between test, match, replace, or split modes to simulate your real-world use case.
Inspect Matches & Groups
View match tables with positions, lengths, and capture groups (named or numbered). Replacement previews show before/after output for confidence.
Understand the Pattern
Leverage the pattern explanation panel to break down tokens, quantifiers, anchors, and lookarounds so teams can document complex expressions.
Problems It Solves
Problem
Regex bugs surface late because developers lack a safe environment to test complex patterns against sample data.
Solution
Run patterns against multiple inputs, switch between match modes, and inspect live output to validate logic before deploying.
Problem
Capture group behavior is hard to visualize, leading to brittle replace operations or misaligned parsing.
Solution
Detailed tables show each group’s content, start, and length so you can fine-tune replacements or parsing strategies confidently.
Problem
Team members struggle to understand advanced regex syntax when onboarding or reviewing code.
Solution
Pattern explanations highlight anchors, character classes, quantifiers, and lookarounds, turning cryptic expressions into readable documentation.
Why Choose This Tool
Real-Time Feedback
Instant execution keeps validation fast as you edit, making it easier to iterate on complex patterns without context switching.
Private by Design
Regex inputs, sample data, and results stay inside your browser, protecting logs, customer data, and proprietary patterns.
Productivity Enhancers
Keyboard shortcuts, copy/download buttons, dark mode, and history tracking support power users working through large test suites.
Full JavaScript Feature Set
Support for dotAll, unicode, lookbehinds, and sticky flags ensures parity with modern JavaScript engines and runtime behavior.
Frequently Asked Questions
What regex flags are supported?
How do I test against multiple inputs?
Can I see capture groups?
What test modes are available?
How does pattern explanation work?
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