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developer validator

Regex Tester

Test regex patterns against sample text with live matches and errors.

Results

Processing…
Pattern status
Processing...
Matches / errors
Processing...

Rules & checks

Uses JavaScript RegExp constructor with provided flags.

Returns compilation errors if the pattern is invalid.

Shows matched groups when available.

When to use it

  • Test patterns before merging input validation
  • Debug production errors caused by malformed regex
  • Validate search filters or routing rules in a safe sandbox

Common errors

  • Unescaped backslashes
  • Unclosed groups
  • Unsupported flags

Tips

  • Escape backslashes (\\d instead of \d in some contexts)
  • Start with simpler patterns to narrow down errors

Examples

Valid pattern

  • Pattern: \d{3}
  • Sample: Order 123 ships
  • Matches: 123

Invalid pattern

  • Pattern: ([a-z
  • Error: Unterminated group

FAQs

Do you store my patterns or samples?
No. Everything stays in your browser.
Which flavor is used?
JavaScript RegExp. Behavior may differ from PCRE or other engines.

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For quick testing. Always mirror patterns and tests in your codebase.