R101
Developer ToolsFree In-Browser / WASM

Regex101

Interactive regular expression tester, explainer, and visual debugger.

Visit Official Website
🔒 External link to regex101.com. Verified clean & active.
Account Required No signup needed
Pricing StructureFree
Execution ModeClient-Side (In-Browser)
Last Inspected2026-08-27

About Regex101

Regex101 is the indispensable regex scratchpad for developers. It highlights pattern matches instantly as you type, extracts capture groups with index offsets, and explains every token in plain English in the side panel. It includes a regex visualizer, code generator in 8+ languages, and a catastrophic backtracking debugger.

Best for: Developers crafting input validation rules, search queries, and parsing algorithms.

Pros & Cons Analysis

What We Liked
  • The absolute gold standard for regex debugging and learning
  • Code generator generates ready-to-paste snippets in Python, JS, Go, and C#
  • Completely free with community regex library
Considerations & Limits
  • Can feel overwhelming to beginners due to high density of developer controls

Key Features & Capabilities

Multiple regex engines (PCRE2, JavaScript, Python, Go, Java, .NET)
Plain-English token explanation panel
Interactive match capture group inspector
Catastrophic backtracking debugger and step counter
Unit testing suite for regex patterns

Pricing & Plan Information

100% Free; Optional donation supporter perks.

Specifications

Supported Formats
REGEXPCREJSPYTHONGO
Available Platforms
Web
Developer / Team: Firas Dib

Associated Tasks

Regex Tester & DebuggerJSON Formatter & ValidatorCrontab Expression Generator & Explainer

Ready to use Regex101?

Launch the official Regex101 web app in a new tab to complete your document or image task.

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