Spreadsheet Composer is an Excel add-in, which offers significant productivity and development benefits. The core capability of the add-in is the 'compose' function. With this function it is possible to define a spreadsheet calculation as a series of linked steps and then automatically 'compose' the calculation into a single complex formula. Spreadsheet Composer is a very powerful tool that enables the user to attain a level of functionality and error trapping that was previously difficult to achieve in a manageable spreadsheet. The add-in provides a number of support features to facilitate the use and management of composed formulae. It provides a database for the storage; documentation and retrieval of formulae and a 'matching' function that can link an implemented formula back to its database description. The retrieval function allows the user to copy a formula from the database into a selected spreadsheet cell, to automatically select input cells for the formula and to specify a mix of relative and absolute addressing for the selected cells. The add-in permits complete verification of a formula before it is stored within the database. The formula can be verified against its original definition and against its intended behaviour. If a formula gives an unintended output for a particular combination of inputs, then additional error trapping can be factored into the composed formula. The add-in provides an 'export' function, which allows a completed spreadsheet to be written out to a standalone workbook for independent operation. Further details of Spreadsheet Composer are provided within the download. It includes an extensive description document incorporating numerous screen-shots.