Valid pattern
- Pattern: \d{3}
- Sample: Order 123 ships
- Matches: 123
developer validator
Regex Tester
Test regex patterns against sample text with live matches and errors.
Results
Paste input and validate locally.- Pattern status
- Ready when you validate.
- Matches / errors
- Ready when you validate.
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
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.