Develop Excel Add-in

We need help from an experienced developer to create an Excel Add-in, compatible with Excel 2007, 2010 and 2013, that will be bundled with our web solution. It will be used to view, change or add data in certain tables and/or views in the web solutions SQL database. The plugin will include – but not limited to - a branded ribbon containing : 1. Connect buttons – one for each view/table 2. A refresh button  3. A update button to send any changes or additions back to the database The user flow should be as follows: 1. User downloads Excel file from our web solution. When file is opened the add-in should automatically load. 2. User load data by clicking on one table/view button in ribbon. This fetches the data from the database and presents it to the user. (Filter possibilities is preferred but not a must initially). 3. User interacts with data, and makes changes and/or row additions 4. User then clicks on update button which - validates data - checks if updates has been made by other users to the database in the time from load in Excel, if so a warning message is presented and update cancelled - writes/updates data to SQL database (if checks are ok) The plugin should be developed to be easily extensible in future, e.g. adding future views/tables including documentation on how to. Plugin could be developed either as a .xla or as a .xll depending upon the selected developers preferences and suggestions. There may also be requirement/opportunity for further outside development on the tool after the initial delivery.