We have been using Xlsio for last 3 years. Before buying syncfusion we evaluated many 3rd party products and worked with their support team during the evaluation period. Finally we chose Syncfusion Xlsio component. No other product came close to syncfusion. Users in our organization use MS office excel for their day to day task. The excels has macros, formulas, graphs, support creating/manipulating excel sheets on fly ,etc. Apart from XLSIO other advantage we found using Syncfusion.Calculate.Base api (which comes with the Sycnfusion back office) was when we had formulas which are in strings and needs to be parsed inorder to calculate the value. The driving factor in buying Syncfusion xlsio was that we needed to get away with office installation on servers and use xlsio api to develop applications that worked with the excel file in a very short time frame. The advantage of using xlsio api is that it is very easy to use , the support docs are well documented, the support staff is pretty quick in responding to issues. I would definetly recommend Syncfusion XlsIO to anyone that needs to use Excel or build applications around excel in their organization.