Regex Tester and Explainer

Test JavaScript regular expressions safely with try/catch, inspect matches, and see basic token explanations.

Flags
Matches and explanation 

        

    

                

            
                    

                        
How to use this tool

                        
    
                                                            
  1. Enter a regex pattern without surrounding slashes.
    2. 
                                                            
  2. Choose supported JavaScript flags such as g, i, m, s, u or y.
    3. 
                                                            
  3. Paste test text and run the matcher.
    4. 
                                                    

                    


                    

                        
Common mistakes

                        
    
                                                            
  • Forgetting to escape backslashes when moving regex into a string.
    • 
                                                            
  • Using catastrophic patterns on very large text.
    • 
                                                            
  • Expecting PCRE-only syntax to work in JavaScript RegExp.
    • 
                                                    

                    


                    

                        
FAQ

                        

                                                            

                                    Does this use eval?
                                    
No. It creates a RegExp object with try/catch.

                                

                                                            

                                    Which regex engine is used?
                                    
The browser JavaScript RegExp engine.

                                

                                                            

                                    Is the explanation complete?
                                    
No. It explains common tokens and patterns as a practical helper.

                                

                                                    

                    


                        

        
Related tools

        

                                                
                        JSON
                        JSON Validator and Formatter
                        
Validate JSON, format it for reading, or minify it for compact API payloads without sending data to an external API.

                    
                                                                
                        Cron
                        Cron Expression Explainer
                        
Explain common five-field cron expressions and catch basic schedule mistakes before adding a job to production.

                    
                                                                
                        OpenAI
                        OpenAI API Request Checker
                        
Statically inspect an OpenAI API request body for common JSON and parameter mistakes before sending it to the API.

                    
                                    

    

                                            
Last updated: May 17, 2026