\d+ β item42 β 42Use a small sample containing both a match and a nonmatch before testing a large document. The example below selects the digits in item42 with a digit pattern and the global flag. Read the match text and position, then change one input at a time to understand the result. Copy the expression only after checking the edge cases that matter to your application.
The tester uses JavaScript regular expressions, so syntax accepted by another engine may differ. A timeout can stop expensive matches; it is not proof that a pattern will perform well on every input. Empty matches are advanced safely, but you still need explicit tests for Unicode, multiline text, and your selected flags.
Pattern: \d+; flags: g
Text: item42
Match: 42
Regular expressions (regex) are powerful pattern-matching tools that use special syntax to define search patterns for text. They include literal characters, metacharacters, character classes, quantifiers, anchors, and groups for matching, validating, and extracting data from text.
Our tester supports standard regex syntax including character classes, quantifiers, anchors, alternation, grouping, and all standard flags (global, case-insensitive, multiline, unicode, dotAll, sticky). Advanced features include lookarounds, named groups, and backreferences.
The tool provides instant pattern validation, live match highlighting, syntax error detection, performance metrics, and detailed debugging information including match groups, capture analysis, and pattern explanations with visual feedback.
Our pattern library includes validation patterns (email, phone, URL), extraction patterns (dates, numbers, text), processing patterns (HTML, code, formatting), and specialized patterns for web development, data science, and system administration.
Processing runs in your browser. Choosing Share uploads the selected tool state; anyone with the link can open it. Signing in to save sends content to your account library and records save history. Review the selection before either action. Closing the page does not delete those copies. Copying locally does not create a server share.
Enter a pattern and test string to see matches