RegexpLint helps you understand and analyze regular expressions.

We graphically render regular expressions and point out common pitfalls.

Enter a regular expression or try example 1 · example 2 · example 3

Use the table below as a cheat sheet:

`[abc]` |
a, b or c | `.` |
any single character | `a?` |
zero or one of a |

`[^abc]` |
any character except a, b, or c | `\s` |
whitespace | `a*` |
zero or more of a |

`[a-z]` |
range a-z | `\S` |
non-whitespace | `a+` |
one or more of a |

`[a-zA-Z]` |
a-z or A-Z | `\d` |
any digit | `a{n}` |
exactly n of a |

`^` |
anchor at start of line | `\D` |
any non-digit | `a{n,}` |
n or more of a |

`$` |
anchor at end of line | `\w` |
any word character (letter, number, underscore) | `a{n,m}` |
between n and m of a |

`(...)` |
capture everything enclosed | `\W` |
any non-word character | `a*?` |
zero or more of a (non greedy) |

`(a|b)` |
a or b | `\b` |
any word boundary | `(a)...\1` |
back reference |

`(?=a)` |
look ahead (positive) | `(?!a)` |
look ahead (negative) | `\B` |
any non-word boundary |