C# Regex Literal Builder with JavaScript Preview
C# string unescape; C# code literals; JS regex preview. Helps prepare C# string literals and options. Match previews run in JavaScript, so C#-specific regex behavior may differ.
Scope of this tool: Helps prepare C# string literals and options. Match previews run in JavaScript, so C#-specific regex behavior may differ.
How to use
Enter a pattern, choose how it’s written in C#, then run it on your sample text.
- Paste your regex into Pattern (raw regex, C# regular string, or C# verbatim
@""). - Set options like Ignore case, Multiline (
^ $per line), and Singleline (.matches newlines). - Paste test text and click Check & Run to see matches and groups.
FAQ
Does this use the real .NET (C#) regex engine?
No—this runs in your browser using JavaScript regex, so most basics match up but some .NET-specific features can differ.
How do I paste a C# regex string without messing up backslashes?
Set Input mode to C# regular or verbatim, or leave it on Auto-detect and paste "..." or @"...".
What’s the difference between Multiline and Singleline (C#)?
Multiline changes ^/$ 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.
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