Regex Tester

Test regular expressions against sample text using Python-style regex. View raw JSON results from the HeffTools Regex API and integrate the same endpoint into your own tools and automation.

Enter a Python-style regular expression. The pattern is sent to the HeffTools Regex API for evaluation.
Combine flags as characters, for example: i (ignore case), m (multiline), s (dot matches newline).

Matches (JSON Output)

This is the raw JSON response returned by POST /api/v1/regex/test. It is suitable for use in scripts, CI pipelines, and internal tools. 



      
        Backed by POST /api/v1/regex/test
      
    

  


  

  

    
How to Use the Regex Tester

    
    
      
  1. Enter a regex pattern in the Pattern field.
    2. 
      
  2. 
        Optionally provide flags:
        
      
          
    • i – ignore case (case-insensitive matching)
      • 
          
    • m – multiline (anchors ^ and $ match line boundaries)
      • 
          
    • s – dot matches newline (allows . to match line breaks)
      • 
        
    
      
    3. 
      
  3. Paste the test text that you want to search or validate.
    4. 
      
  4. Click Run to send the request to the HeffTools Regex API.
    5. 
      
  5. Review the JSON output to see matches, groups, and any errors.
    6. 
    

  


  

    
Example Patterns

    
    
      
  • \d+ – one or more digits
    • 
      
  • ^#[0-9A-Fa-f]{6}$ – hex color code like #1A2B3C
    • 
      
  • https?://[^\s]+ – simple HTTP/HTTPS URL matcher
    • 
      
  • ^[A-Za-z0-9._%+-]+@[A-Za-z0-9.-]+\.[A-Za-z]{2,}$ – basic email validation pattern
    • 
    

  


  

    
Calling the Regex API from Your Code

    

      This page uses the same JSON API you can use in your own automation:
    

    
POST /api/v1/regex/test
Content-Type: application/json

{
  "pattern": "\\d+",
  "text": "Order 1234 shipped on 2024-01-01",
  "flags": "s"
}


    
Example JSON response (shape may vary):

    
{
  "flags": "s",
  "match_count": 4,
  "matches": [
    {
      "end": 10,
      "groups": [],
      "match": "1234",
      "start": 6
    },
    {
      "end": 26,
      "groups": [],
      "match": "2024",
      "start": 22
    },
    {
      "end": 29,
      "groups": [],
      "match": "01",
      "start": 27
    },
    {
      "end": 32,
      "groups": [],
      "match": "01",
      "start": 30
    }
  ],
  "pattern": "\\d+"
}

  


  

    
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