regex101
regex101 tests and debugs regular expressions with live matches, explanations, and support for several regex engines.
About regex101
regex101 is a web tool for building, testing, debugging and converting regular expressions. It shows real-time matches, explains tokens, groups and flags, and shows match information including named groups and captured values.
It supports PCRE2 (PHP), JavaScript, Python, Golang, Java, .NET 10.0 (C#), Rust, POSIX ERE, POSIX BRE (grep/sed) and PCRE (Legacy). It includes modes for match, substitution, extraction and unit tests, plus tools for code generation, debugging, conversion, match export, benchmarking and formatting. Users can save and share examples and publish to a community library.
Key features
- Test patterns with real-time matches and group capture details
- Explain tokens, groups, and flags for entered pattern
- Convert patterns, flags, and replacement text between supported flavors
- Debug regex execution to investigate unexpected results
- Export matches to JSON, JSON Lines, CSV, or Plain Text
- Run substitution, extraction, and unit tests on patterns
Best for: People who need to test, explain, and convert regular expressions across different engines.
Good for
- Supports PCRE2, JavaScript, Python, Golang, Java, .NET, Rust and POSIX flavors
- Explains tokens, groups and flags with match and capture details
- Includes converter, debugger, code generator and match export tools
regex101 at a glance
- Website
- regex101.com
- Category
- Development › Developer Tools
- Type
- Online tool
- Pricing
- Not confirmed. Check the site
- Platforms
- Web
- Open source
- Not stated
- Language
- English
- Last checked
- Oct 5, 2026 · Online when checked
- Listed
- Oct 5, 2026
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regex101 FAQ
Which regex flavors does regex101 support?
PCRE2 (PHP), JavaScript, Python, Golang, Java, .NET 10.0 (C#), Rust, POSIX ERE, POSIX BRE (grep/sed), and PCRE (Legacy).
What formats can matches be exported to?
JSON, JSON Lines, CSV, or Plain Text.
Can I save and share regex examples?
Yes, the editor includes Save & Share and Publish to Community Library options.
Is something wrong or out of date?
Tell us and an editor will check it.
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