Free Developer Tool — 100% Client-Side

Regex Tester

Test regular expressions in real-time with match highlighting, group capture, and flag controls.

/ /
2 matches

Matches

 
 
     
 
 
 
 
 Sponsored 
 Advertisement 
 
  
 
 
What Is a Regex Tester?
 

A regex tester is an interactive tool that helps developers write, test, and debug
        regular expressions (regex) in real-time. It shows exactly which parts of your input text match
        your pattern, making it invaluable for building and troubleshooting regex patterns for validation,
        search, parsing, and text transformation tasks.

 
Common Regex Patterns
 
 
 
Email
 \w+@\w+\.\w+ 
 
 
Phone (US)
 \(\d3\)\s\d3-\d4 
 
 
URL
 https?://\S+ 
 
 
IP Address
 \d3\.\d3\.\d3\.\d3 
 
 
Understanding Regex Flags
 
 
 
g — Global
 
Find all matches, not just the first one.
 
 
 
i — Case-Insensitive
 
Ignore case when matching letters.
 
 
 
m — Multiline
 
^ and $ match line boundaries, not string boundaries.
 
 
 
s — Dotall
 
The . metacharacter matches newlines too.
 
 
 
Use Cases for Regex Testing
 
     
  • Form Validation — Validate email addresses, phone numbers, URLs, and postal codes in web forms.
    •  
  • Log Parsing — Extract structured data from server logs, application logs, and error reports.
    •  
  • Data Extraction — Pull specific patterns from large text documents, API responses, or configuration files.
    •  
  • Search & Replace — Find and transform text patterns across files with regex-based substitution.
    •  
  • Input Sanitization — Filter and clean user input by matching allowed or disallowed patterns.
    •  
 
How to Use This Regex Tester
 

Enter your regex pattern between the forward slashes in the pattern input field. Add flags (g, i, m, s, u)
        using the flag buttons or the flags input. Type or paste your test string in the text area below.
        Matches are highlighted in real-time with colored backgrounds, and capturing groups are displayed
        in the groups section below the matches. If your regex is invalid, an error message will show
        the syntax problem.

 
 
 
 Sponsored 
 Advertisement 
 
  
 
 
 
Regular expressions are patterns used to match character combinations in text — one of the most powerful tools in a developer's arsenal. From validating email addresses and phone numbers to extracting data from logs and performing search-and-replace across thousands of files, regex is essential for text processing. A regex tester provides real-time feedback showing exactly which parts of your test string match the pattern, what each capture group extracts, and how flags (g, i, m, s) affect matching behavior. This interactive feedback loop is invaluable for debugging complex patterns before using them in code. Testing regex in a dedicated tool is faster than the edit-refresh cycle in application code and helps avoid production bugs caused by incorrect patterns.
 
 
 
 
 
How to Do This in Code
 
 
  
  
 
 
 
 
 
Popular Developer Tools
 
     
 JSON Formatter 
Format, validate, and beautify JSON data
 
     
 Base64 Encoder 
Encode and decode Base64 instantly
 
     
 JWT Decoder 
Decode and inspect JWT tokens
 
     
 Regex Tester 
Test regular expressions in real-time
 
     
 Hash Generator 
Generate MD5, SHA-1, SHA-256 hashes
 
  
 
 
 
 
 
 
 
 
 
 
Need a Fast Code Editor?
 
Write, edit, and refactor code with a modern editor built for speed and productivity.
 
  VS Code     Cursor     
 
 
 
 
 
 
 
 
Related Tools
 
  
JSON Formatter
 
Format, validate, and beautify your JSON data with syntax highlighting and error detection.
  
Case Converter
 
Convert text between camelCase, snake_case, kebab-case, and more.
  
Text Diff Checker
 
Compare two texts side by side and highlight the differences between them.
  
 
 
 
 
Regex Tester FAQ
 
 
  What regex flavors are supported?     
This tool uses JavaScript's RegExp engine, which follows the ECMAScript specification. It supports most common patterns including groups, lookaheads, and quantifiers.
 
  What do the flags do?     
g = global (find all matches, not just first), i = case-insensitive, m = multiline (^ and $ match line boundaries), s = dotAll (. matches newlines).