Skip to tool
All tools
FeuTex · free tools runs in-browser no bloat built by LiMiT

Regex Checker (C#)

Validate a C#-style regular expression and test it on sample text. You’ll get match lists, capture groups (including named groups), and copy-ready C# snippets for string literals and RegexOptions.

Note: This tool runs in your browser using the JavaScript regex engine. It’s great for quick checks, but always confirm final behavior in .NET for engine-specific features.

Category: Developer · URL: /tools/regex-checker-c.html
Runs locally. No network requests. 

    


    

      Related tools
      
    

  



          

          

            Privacy: runs locally in your browser. No uploads, no tracking scripts.
          

        

      


      
    


    

      
How to use

      
Enter a pattern, choose how it’s written in C#, then run it on your sample text.
  1. Paste your regex into Pattern (raw regex, C# regular string, or C# verbatim @"").
  2. Set options like Ignore case, Multiline (^ $ per line), and Singleline (. matches newlines).
  3. Paste test text and click Check & Run to see matches and groups.

      

        Keywords this page targets (natural cluster): regex checker c#, c# regex tester, dotnet regex tester online, validate regex pattern c#, test regex against text c#, c# regex named groups tester, c# regex capture groups, c# verbatim string regex, escape regex in c# string, regexoptions ignorecase multiline singleline, regex match indices c#, debug regex pattern c#, c# regex quick check, convert c# string literal to regex, regex dotall singleline c#, multiline caret regex c#, c# regex word boundary, generate c# regex code snippet, regex pattern compile error c#
      

      

        Secondary intents covered: Check whether a C# regex pattern is syntactically valid, Test a regex against sample input and list all matches, Inspect capture groups and named group values, Convert between C# string literal forms (regular vs verbatim) and the actual regex pattern, Generate a C# code snippet with RegexOptions for reuse, Troubleshoot multiline vs singleline (dotall) behavior, Quickly confirm word boundaries, anchors, and quantifiers on example text, Copy a normalized pattern output for pasting into code
      

    


    

      
FAQ

    
Does this use the real .NET (C#) regex engine?
No—this runs in your browser using JavaScript regex, so most basics match up but some .NET-specific features can differ.
How do I paste a C# regex string without messing up backslashes?
Set Input mode to C# regular or verbatim, or leave it on Auto-detect and paste "..." or @"...".
What’s the difference between Multiline and Singleline (C#)?
Multiline changes ^/$ to work per line; Singleline makes . match newlines.
Can I see capture groups and named groups?
Yes—each match lists numeric groups and (when supported by your browser) named groups like (?<name>...).
Why might a pattern work in C# but fail here (or vice versa)?
Engine differences exist (feature support, escaping, lookbehinds, Unicode classes), so treat this as a fast check and confirm in .NET.
How do I generate a copy-paste C# snippet?
The output includes a ready new Regex(@"...", RegexOptions...) line plus both regular and verbatim string literal versions.
Is my data sent to a server?
No—this tool runs locally in your browser and does not make network requests.