Online Regex Tester & Visualizer
Test, debug, and visualize Regular Expressions against custom text instantly. Real-time ECMAScript regex engine running safely in your browser.
Generate a public link to share this regex with others.
Note: Regex shared publicly will be saved to our servers.
Introduction
Build, test, and debug complex Regular Expressions in real-time. Instantly visualize your matches, capturing groups, and lookarounds.
What is the Regex Tester and Why Use It?
Regular Expressions are incredibly powerful but notoriously difficult to write and debug. A single misplaced quantifier or missing escape character can cause catastrophic backtracking or failed validations. Our Regex Tester provides an interactive environment to build expressions safely. Type your regex and see matches instantly highlighted against your test data. Since the engine is powered by your browser's native JavaScript execution, you get 100% accurate feedback for web applications without any data privacy risks.
Key Features
- 100% Client-Side Execution: Your test data (which often includes real emails, phone numbers, or logs) is never sent to a server.
- Real-Time Highlighting: Matches are color-coded in real-time as you type, allowing you to visually see what your regex is capturing.
- Capturing Group Analysis: Breakdowns the exact string captured by each numbered or named group in the sidebar.
- Flag Toggling: Easily toggle global (`g`), case-insensitive (`i`), and multiline (`m`) flags via the UI.
How to Use the Regex Debugger (Step-by-Step)
- Step 1: Type your regular expression into the top input bar and select your desired flags.
- Step 2: Paste your sample text or log data into the main testing area.
- Step 3: Review the highlighted text to verify your matches. Check the sidebar to inspect specific capturing groups or error warnings.