Implementations generally relate to a spreadsheet add-in that provides data entry validation. As described in more detail herein, the spreadsheet add-in integrates a spreadsheet-based table component with a remote web service. The spreadsheet add-in uses web service metadata to validate data that a user enters into the spreadsheet. The spreadsheet add-in provides immediate feedback on errors in an interactive fashion for the user. Furthermore, during a data upload process, any errors that are reported by the web service are displayed in context such that the user may quickly affect corrections.