What is Regex101?
Regex101 is the place many developers go to write and check regular expressions. You type a pattern and some test text, and the page highlights every match and capture group as you type, with a quick reference of tokens on the side. It supports PCRE2 for PHP, JavaScript, Python, Golang, Java, .NET, Rust, POSIX ERE and BRE for grep and sed, and legacy PCRE.
Beyond simple matching it has modes for substitution, extraction, unit tests and multi-step pipelines, plus a code generator, a step-by-step debugger and a converter between flavors. You can save and share a regex with a link or publish it to the community library. The core tester is free, while Regex101 Pro unlocks deeper tools such as explanations, benchmarking, formatting and file workflows.
Main Features
- Live match and capture group highlighting as you type
- Ten flavors including PCRE2, JavaScript, Python, Go, Java, .NET, Rust and POSIX
- Match, Substitution, Extraction, Unit Tests and Pipeline modes
- Code generator that turns your regex into ready-to-paste code
- Regex debugger with a free 50-step PCRE2 preview
- Export matches to JSON, JSON Lines, CSV or plain text
- Save and share links plus a public community library
- Pro adds explanations, benchmarking, formatting and file loading
How to Get Started with Regex101
- Open regex101.com and pick your language flavor on the left.
- Type your pattern in the regular expression box and set flags.
- Paste sample text into the test string box and check the highlighted matches.
- Use Save & Share to get a link, or the code generator to copy code.
Regex101 Pricing
Regex101 is free to use for matching, unit tests, the code generator, two test strings, a 50-step debugger preview and converting any flavor to JavaScript. Regex101 Pro costs €7 per month billed monthly, or €4.99 per month billed yearly, and adds explanations, longer debugger traces, conversion to every flavor, benchmarks, formatting, color schemes, Office, PDF and multi-file operations, substitution pipelines and an ad-free workspace. An Enterprise self-hosted option is priced per seat with optional add-ons.
Who Should Use It?
- Developers writing validation or parsing patterns
- Students learning regular expressions
- Data analysts cleaning text with find and replace
- DevOps engineers writing grep and sed commands
- Teams sharing tested patterns in code reviews
Regex101 Alternatives
- Replit AI: a browser coding workspace where you can run full scripts that use your regex.
- Warp: a modern terminal that helps when you are testing grep and sed commands.
- CodeRabbit: automated code review that can catch risky patterns in pull requests.
Frequently Asked Questions
Is Regex101 free?
Yes. The main regex tester, unit tests, code generator and sharing are free. Regex101 Pro costs €7 a month, or €4.99 a month billed yearly, and adds explanations, longer debugging, benchmarks, formatting, file tools and an ad-free workspace.
Which regex flavors does Regex101 support?
Regex101 supports PCRE2 for PHP, JavaScript, Python, Golang, Java, .NET 10.0 for C#, Rust, POSIX ERE, POSIX BRE for grep and sed, and legacy PCRE. Pick the one your code uses so the matches you see are the matches you will get.
Does Regex101 send my test strings to a server?
Regex101's docs say matching, debugging, benchmarks and file extraction run locally in your browser. Data is only sent when you choose to save, share or use connected features, so you can test patterns against sample data without uploading it.