Regex Tester
Test and debug regular expressions with live match highlighting
Developer Tools That Respect Your Data
Developers reach for small utilities dozens of times a day — formatting JSON, testing a regex, generating a UUID, encoding Base64, minifying CSS, converting a timestamp. Each of these tasks is trivial individually, but collectively they consume meaningful time and break focus. Good developer tools reduce each one to a single paste-and-copy action.
The most important property of a developer utility is trust. When you paste an API response to format it, you might be pasting real credentials, customer data, or production configuration. A tool that sends your input to a server creates a risk every time you use it. A tool that runs entirely in your browser creates none. Every developer tool on ToolsHub processes your data locally — nothing is transmitted, stored, or logged — so you can safely paste real values without first scrubbing them.
Consistency matters too. A JSON formatter, a regex tester, and a diff checker should all behave the way you expect them to, with predictable keyboard shortcuts, clear error messages, and output you can copy with one click. The goal is for the tool to disappear into your workflow — to be so fast and familiar that you never have to think about the tool itself, only about the problem you are solving.
About Regex Tester
Test, debug, and learn regular expressions interactively with our free Regex Tester. Enter your regex pattern, provide test text, and see all matches highlighted in real time — with capture groups, flags, and detailed match information.
Regular expressions are one of the most powerful tools in a developer's arsenal — and one of the most notoriously difficult to write correctly. A misplaced character or forgotten flag can mean the difference between a working validation and a security vulnerability. Testing regex patterns before deploying them in production code is essential.
Our Regex Tester provides an interactive environment where you can write patterns, see matches highlighted in the test text, inspect capture groups, test different flags (global, case-insensitive, multiline), and understand what your regex is actually matching — all in real time.
Common Use Cases
Key Features
How to Use Regex Tester
- 1
Enter your regular expression in the pattern field
- 2
Set any needed flags (g for global, i for case-insensitive)
- 3
Paste your test text in the input area
- 4
See matches highlighted in real time as you type
- 5
Review the match list below to see capture groups and positions
Why Use Regex Tester?
Debug Without Deploying
Test your regex against real data before embedding it in production code. Catch edge cases and unexpected matches that would cause bugs in your application.
Learn Regex Interactively
The best way to learn regex is through immediate feedback. Write a pattern, see what it matches (and what it doesn't), and adjust until your understanding is correct.
Build Complex Patterns Safely
Complex patterns for email validation, URL matching, or phone number parsing have many edge cases. Test them against a comprehensive set of test strings before using in production.
Document Complex Patterns
Use our tool to demonstrate what a complex regex pattern does to teammates or document it for code reviews. The highlighted output makes regex behavior immediately understandable.
