Regex Tools

Regex Builder

Regex Builder builds a regular expression from token buttons for anchors, character classes, groups, and quantifiers, then tests it live.

Client-sideRuns entirely in your browser — your data never leaves your device.

Regex Builder is a free Regex Tools utility that runs entirely in your browser — nothing you enter is uploaded.

Test text
Matches




Pattern explanation



  
How to use Regex Builder

  
    
      
  1. Enter or paste your pattern and test string into the input field to begin.
    2. 
      
  2. Adjust the Literal text, Built pattern, Flags options to match what you need.
    3. 
      
  3. Click Add literal to process it instantly in your browser.
    4. 
      
  4. When it looks right, Copy pattern to save it.
    5. 
  

  
About this tool

  
There is no server behind Regex Builder. Regex Builder runs your pattern locally with the JavaScript engine and shows captures live.

  
Flags and group captures are surfaced so you can refine the pattern quickly. Nothing you enter is uploaded, and it keeps working offline once the page has loaded.

  
Frequently asked questions

  

      
What does Regex Builder do?
Use Regex Builder to process your input without installing anything using the Literal text, Built pattern controls; everything happens client-side.

      
Is Regex Builder free to use?
Yes — Regex Builder is completely free, with no usage limits.

      
Is my input private in Regex Builder?
Yes — your input never leaves your device; Regex Builder does all the work in your browser.

      
Which regex flavor does Regex Builder use?
Regex Builder runs your pattern with the browser's own JavaScript regex engine, live and on your device.

      
Does Regex Builder work on mobile?
Yes — Regex Builder is just a web page and runs on any modern browser, including phones and tablets.

  

  
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