public  string contextUrl = System.Configuration.ConfigurationManager.AppSettings["SiteUrl"];

[Route("SaveProject")]
[HttpPost]
public IHttpActionResult SaveProject(SaveProjectViewModel projectViewModel)
{

    string sharepointTemplate = "{025A81C1-D660-4191-9E04-28FE88399CCC}#Support Project Template";
    bool isActivepro = true;
    string title = "JJ";
    string description = "JJ DESC";
    string templateId = sharepointTemplate;
    bool isProjectActive = isActivepro;

    string userName = System.Configuration.ConfigurationManager.AppSettings["UserName"];
    string password = System.Configuration.ConfigurationManager.AppSettings["PassWord"];
    var securePassword = new SecureString();
    foreach (char c in password.ToCharArray())
    {
        securePassword.AppendChar(c);
    }
    using (ClientContext clientContext = new ClientContext(contextUrl))
    {
        clientContext.AuthenticationMode = ClientAuthenticationMode.Default;
        clientContext.Credentials = new SharePointOnlineCredentials(userName, securePassword);
        Microsoft.SharePoint.Client.Web oWebsite = clientContext.Web;
        clientContext.Load(oWebsite);
        //clientContext.ExecuteQuery();

        //CreateNewSite(clientContext, title, description, templateId);

        int siteLanguage = 1033;
        // clientContext.AuthenticationMode = ClientAuthenticationMode.Default;

        Microsoft.SharePoint.Client.Web webSite = clientContext.Web;
        clientContext.Load(webSite, wde => webSite.Webs);
        clientContext.ExecuteQuery();

        var subWeb = (from w in webSite.Webs where w.Title == title select w).SingleOrDefault();

        if (subWeb == null)
        {
            //Create a new webCreateInformation object to specify the properties of the new site being created.

            WebCreationInformation webCreateInfo = new WebCreationInformation();
            webCreateInfo.Description = description;
            webCreateInfo.Language = siteLanguage;
            webCreateInfo.Title = title;
            webCreateInfo.Url = title;
            webCreateInfo.UseSamePermissionsAsParentSite = true;
            webCreateInfo.WebTemplate = templateId;

            //Adding a new site under the root web

            Microsoft.SharePoint.Client.Web newWebsite = webSite.Webs.Add(webCreateInfo);

            // Retreiving the server properties to the client context. Here we are retreiving the web server url and the time it was created.

            clientContext.Load(newWebsite,
                Website => Website.ServerRelativeUrl,
                Website => Website.Created);
            clientContext.ExecuteQuery();
        }
        else
        {
                   // site already exist.
        }

        //Save Project To List

        List list = clientContext.Web.Lists.GetByTitle("Project List");
        clientContext.Load(list);
        var getSiteName = new CamlQuery();
        getSiteName.ViewXml = "<View><Query><Where><Eq><FieldRef Name='Title'/><Value Type='Text'>" + title + "</Value></Eq></Where></Query></View>";
        ListItemCollection listItems = list.GetItems(getSiteName);
        clientContext.Load(list);
        clientContext.Load(listItems);
        clientContext.ExecuteQuery();

        if (listItems.Count == 0)
        {
            ListItemCreationInformation itemCreateInfo = new ListItemCreationInformation();
            ListItem listItem = list.AddItem(itemCreateInfo);
            FieldUrlValue hyper = new FieldUrlValue();
            hyper.Description = title;
            hyper.Url = contextUrl + title;
            listItem["Title"] = title;
            listItem["Project_x0020_Name"] = hyper;
            listItem["IsActive"] = title;
            listItem.Update();
            // Executes the query to retreive the required information from the server.
            clientContext.ExecuteQuery();
        }
        else
        {
                    //item already exist in list.
        }

    }

    return Ok(new
    {
        NewId = '1',
        Message = "Sucessfully saved project.",
        IsSuccess = true
    });

}

<input type="button" value="Save" onclick="OnSaveClick()">
<script>
    function OnSaveClick() {

            $.ajax({
                type: "post",
                url: 'http://localhost:myhost/api/Project/SaveProject',
                data: {
                    //'Id': '101',
                    //'Description': 'this is a test project',
                    //'Name': 'VSO Test Project 1',
                    //'IsActive': '1',

                    //'SharepointTemplateID': 4,

                },
            }).done(function (data) {
                debugger;
                if (data.IsSuccess) {
                } else {

                }

            }).fail(function (jqXHR, textStatus) {
                toastr["error"](jqXHR + textStatus);
            });
    }

    </script>