<PackageReference Include="System.Configuration.ConfigurationManager" Version="10.0.0" />

System.Configuration.ConfigurationManager

public static class ConfigurationManager
Provides access to configuration files for client applications. This class cannot be inherited.
namespace System.Configuration { public static class ConfigurationManager { public static NameValueCollection AppSettings { get; } public static ConnectionStringSettingsCollection ConnectionStrings { get; } public static object GetSection(string sectionName); public static void RefreshSection(string sectionName); public static Configuration OpenMachineConfiguration(); public static Configuration OpenMappedMachineConfiguration(ConfigurationFileMap fileMap); public static Configuration OpenExeConfiguration(ConfigurationUserLevel userLevel); public static Configuration OpenExeConfiguration(string exePath); public static Configuration OpenMappedExeConfiguration(ExeConfigurationFileMap fileMap, ConfigurationUserLevel userLevel); public static Configuration OpenMappedExeConfiguration(ExeConfigurationFileMap fileMap, ConfigurationUserLevel userLevel, bool preLoad); } }