Build Regex from Example Strings

You know which strings should match but you don't want to write the regex by hand. Paste your examples — phone numbers, product codes, file paths — and this tool infers the pattern: literal where all examples agree, character classes where they differ. A generic-to-specific slider controls how loose the pattern is.

balanced

How to use the Build Regex from Example Strings

Paste example strings. The tool finds positions where all examples agree (becomes literal) and positions where they differ (becomes a character class). The slider adjusts how tight the pattern is:

  • Loose — generic classes (\w, \d, .)
  • Balanced — character ranges where appropriate
  • Strict — specific character sets seen in examples
  • Literal — alternation of all examples