How can I detect if my Flutter app is running in the web?

There is a code written Below to get OS/web where flutter is running...

if(kIsWeb)
   return Text("It's web");

else if(Platform.isAndroid){
     return Text("it's Android"); }

If you want to know what your OS is on the web, you can use

    String platform = "";
    if (kIsWeb) {
      platform = getOSInsideWeb();
    }

    String getOSInsideWeb() {
      final userAgent = window.navigator.userAgent.toString().toLowerCase();
      if( userAgent.contains("iphone"))  return "ios";
      if( userAgent.contains("ipad")) return "ios";
      if( userAgent.contains("android"))  return "Android";
    return "Web";
   }

There is a global boolean kIsWeb which can tell you whether or not the app was compiled to run on the web.

Documentation: https://api.flutter.dev/flutter/foundation/kIsWeb-constant.html

import 'package:flutter/foundation.dart' show kIsWeb;

if (kIsWeb) {
  // running on the web!
} else {
  // NOT running on the web! You can check for additional platforms here.
}

you can use "kIsWeb" to do the job

 if(kIsWeb){
// DO SOMETHING
}else{
// DO ANOTHER THING
}