Regular Expressions 101

Pro

Understand your regular expression with explanations of its tokens, groups, quantifiers, and flags.

Visualize your pattern with interactive regex railroad diagrams. Follow branches and repetitions, select a part to read its explanation, and save diagrams as SVG or PNG.

Refine regexes faster with . Turn examples into patterns, fix mismatches, and build tests to check your changes.

Supports: PCRE2 (PHP), JavaScript, Python, Golang, Java, .NET 10.0 (C#), Rust, POSIX ERE, POSIX BRE (grep/sed), PCRE (Legacy)

Test your regular expression against text and inspect every match, capture group, and named group. Reuse captured values in replacements and backreferences.

Trace unexpected PCRE2 matches and backtracking with the regex debugger. Export your regex matches to JSON, JSON Lines, CSV, or Plain Text.

Use Regex Converter to adapt patterns, flags, and replacements across regex flavors, with explanations of compatibility changes.

25 tokens