| . | Any character except newline |
| \d | Digit [0-9] |
| \w | Word character [a-zA-Z0-9_] |
| \s | Whitespace |
| \b | Word boundary |
| ^ | Start of string |
| $ | End of string |
| * | 0 or more |
| + | 1 or more |
| ? | 0 or 1 (optional) |
| {n,m} | Between n and m times |
| [abc] | Character class |
| (abc) | Capture group |
| (?:abc) | Non-capture group |
| a|b | Alternation (or) |
| (?=a) | Positive lookahead |
| (?!a) | Negative lookahead |
| (?<=a) | Positive lookbehind |
| (?<!a) | Negative lookbehind |
| \1 | Back reference |
| (?<name>) | Named capture group |
RegexTester lets you build, test, and debug regular expressions in real-time. See matches highlighted as you type your pattern. Includes a cheat sheet, pattern library, regex explanation, and match export features.
Enter your regex pattern and test string. Matches are highlighted instantly as you type. Use the flags toggles for case-insensitive, global, multiline, and dotAll matching. Switch tabs to see groups, replace results, pattern explanations, or browse the pattern library.
Real-time match highlighting with alternating colors, capture group analysis, replace mode with back-references, regex explanation/tokenizer, 25+ common pattern library, test history, match export (JSON/CSV/Text), URL sharing, and multilingual UI (English, Korean, Japanese, Chinese).
Regular expressions are powerful but notoriously tricky to get right. RegexTester gives you instant visual feedback so you can iterate quickly and confidently. The built-in explanation feature helps you learn as you go.
Yes! RegexTester is completely free with no signup required. Your data stays in your browser.