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About Regex Tester & Debugger

Test and debug regular expressions with real-time matching, capture group visualization, and a library of common patterns. See matches highlighted instantly as you type. Perfect for developers learning regex or building complex pattern matching. Works offline in your browser.

How to Use

  1. 1Enter your regex pattern in the pattern field
  2. 2Select flags (g, i, m, s, u) as needed
  3. 3Paste your test string in the input area
  4. 4View matches highlighted with capture group details
  5. 5Use the pattern library for common expressions
  6. 6Try find & replace to test substitutions

Key Features

  • Live matching as you type
  • All regex flags supported (g, i, m, s, u)
  • Capture group highlighting and extraction
  • Named capture group support
  • Pattern library with common expressions
  • Find and replace testing
  • Match index and position display
  • Regex explanation for patterns

Common Use Cases

Building and testing validation patternsLearning regular expressions interactivelyDebugging pattern matching issuesExtracting data from textTesting search and replace operations

Frequently Asked Questions

What do the regex flags mean?

g = global (all matches), i = case-insensitive, m = multiline, s = dotAll (. matches newlines), u = unicode support.

Why doesn't my pattern match?

Common issues: forgetting to escape special characters (\., \?, \*), missing global flag for multiple matches, or incorrect anchors (^ $).

Privacy First

All processing happens directly in your browser. Your files never leave your device and are never uploaded to any server.

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