Regex101
Claim this toolBuild, test, and debug regular expressions with real-time explanations and code generation.
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Tracked since2026
0 reviews trackedThe Bottom Line
Entry price
Free, no paid tier
Biggest pro
Provides instant visual feedback on regex matches and errors.
Biggest con
Requires an internet connection to use.
TL;DR - Regex101
- Interactive regex builder and tester with real-time feedback.
- Supports multiple regex flavors and generates code for various languages.
- Includes debugging, benchmarking, and detailed explanations of regex patterns.
Pricing: Free forever
Best for: Individuals & startups
What is Regex101?
Regex101 is an online tool designed to help developers and anyone working with text patterns to create, test, and debug regular expressions. It provides a highly interactive environment where users can input their regex and test strings, receiving instant feedback on matches, substitutions, and a detailed explanation of how the regex works. This real-time analysis helps users understand complex patterns and identify errors quickly.
The platform supports various regex flavors, including PCRE2, PCRE, ECMAScript, Python, Golang, Java, and .NET, making it versatile for different programming environments. Beyond basic testing, it offers advanced features like a code generator to export regex into different languages, a debugger to step through regex execution, and a benchmark tool to evaluate performance. It's ideal for developers, data scientists, and anyone needing to master or efficiently use regular expressions.
Available on: Web
Pros & Cons
Pros
- Provides instant visual feedback on regex matches and errors.
- Supports a wide range of regex flavors, making it versatile.
- Detailed explanations help users understand complex regex patterns.
- Code generation saves time when implementing regex in different languages.
- Debugging and benchmarking tools enhance development efficiency.
Cons
- Requires an internet connection to use.
- Can be overwhelming for absolute beginners due to the sheer number of options.
Preview
Key Features
Real-time regex explanationMatch information displaySubstitution testingUnit test creationCode generator for multiple languagesRegex debuggerRegex benchmark toolSupport for multiple regex flavors (PCRE2, ECMAScript, Python, etc.)
Pricing
Free
Regex101 is completely free to use with no hidden costs.
Reviews
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Regex101 FAQ
What regex flavors are supported for testing and debugging?
Regex101 supports a variety of regex flavors including PCRE2 (PHP), ECMAScript (JavaScript), Python, Golang, Java, .NET 7.0 (C#), Rust, and PCRE (Legacy). This allows users to test their regular expressions against the specific engine they plan to use in their projects.
Can I generate code for my regular expressions directly within Regex101?
Yes, Regex101 includes a Code Generator tool. This feature helps users translate their tested regular expressions into code snippets for various programming languages, streamlining the development process.
How does Regex101 assist in understanding complex regular expressions?
Regex101 provides an automatic explanation of your regex as you type, breaking down its components and their functions. It also displays detailed match information, helping users understand how their regex interacts with the test string.
What debugging capabilities are available for regular expressions?
Regex101 offers a Regex Debugger tool. This allows users to step through their regex execution, observe how each part of the pattern processes the test string, and identify issues more effectively.
Is it possible to save and share regular expressions for later use or collaboration?
Yes, users can save new regular expressions within Regex101. This functionality enables easy sharing and retrieval of regex patterns, facilitating collaboration and personal organization.
Does Regex101 provide tools for evaluating the performance of a regular expression?
Regex101 includes a Benchmark Regex tool. This feature allows users to assess the performance of their regular expressions, which can be crucial for optimizing patterns that will be used on large datasets or in performance-critical applications.
Source: regex101.com