Get all users of SharePoint site using REST API: These users and its data are required to update people field of a SharePoint list. By using below snippet code we can able to get details of a user of SharePoint site. var webURL = _spPageContextInfo.webAbsoluteUrl+"/_api/Web/SiteUsers"; $.ajax({ url: customFieldURL, method: "GET", headers: { "Accept": "application/json; odata=verbose" }, success: function (data) { console.log(data); data.d.results.forEach(function(cm){ console.log(cm.Title+" - "+cm.Email+" - "+cm.Id); }); ...