Get Group Users Using CSOM

The following example returns all the users from the given SharePoint Site Group using SharePoint Managed Client Side Object Model.

 

After creating a console application project in Visual Studio solution, add the following assembly references to the project.

Microsoft.SharePoint.Client

Microsoft.SharePoint.Client.Runtime

using Microsoft.SharePoint.Client;
using System;
using System.Collections.Generic;
using System.Linq;
using System.Net;
using System.Text;

namespace GetGroupUsers
{
    class Program
    {
        static void Main(string[] args)
        {
            //Get Site Url fro user
            Console.Write("Enter Site URL: ");
            string strURL = Console.ReadLine();

            //Get Username from user in the format of (Domain/Login ID)
            Console.Write("Enter UserName (domain/userid): ");
            string strUserName = Console.ReadLine();

            Console.Write("Enter your password: ");
            string pass = getPassword();
            Console.WriteLine();
            RETRY_GROUP:
            Console.Write("Enter Group Name: ");
            string groupName = Console.ReadLine();
            Console.WriteLine();

            try
            {
                ClientContext ctx = new ClientContext(strURL);
                ctx.Credentials = new NetworkCredential(strUserName, pass);
                Web web = ctx.Web;

                Group group = web.SiteGroups.GetByName(groupName);

                //Parameters to receive response from the server
                ctx.Load(web, w => w.Title);
                ctx.Load(group, grp => grp.Title, grp => grp.Users, grp => grp.Owner);
                ctx.ExecuteQuery();

                Console.WriteLine("Groups Name: " + group.Title);
                Console.WriteLine("Users Count: " + group.Users.Count);
                Console.WriteLine("Group Owner: " + group.Owner.Title);
                Console.WriteLine("Users:");
                foreach(User usr in group.Users)
                {
                    Console.WriteLine(usr.Title);
                }
            }
            catch (Exception ex)
            {
                Console.WriteLine("Error: " + ex.Message);
                Console.Write("Do you want to continue (y / n):");
                ConsoleKeyInfo boolContinue = Console.ReadKey();
                Console.WriteLine();
                if (boolContinue.KeyChar == 'y')
                    goto RETRY_GROUP;
                else
                    Console.Write("Enter to Exit.");
            }

            Console.Read();
        }

        private static string getPassword()
        {
            ConsoleKeyInfo key;
            string pass = "";
            do
            {
                key = Console.ReadKey(true);
                // Backspace Should Not Work
                if (key.Key != ConsoleKey.Backspace && key.Key != ConsoleKey.Enter)
                {
                    pass += key.KeyChar;
                    Console.Write("*");
                }
                else
                {
                    if (key.Key == ConsoleKey.Backspace && pass.Length > 0)
                    {
                        pass = pass.Substring(0, (pass.Length - 1));
                        Console.Write("\b \b");
                    }
                }
            }
            // Stops Receving Keys Once Enter is Pressed
            while (key.Key != ConsoleKey.Enter);
            return pass;
        }
    }
}

Supported Versions: 

SharePoint 2013 + SharePoint Online