The Spitzer Science Center (SSC) provides a set of user tools to support search and retrieval of Spitzer Science Archive (SSA) data via the Internet. This paper will present the system architecture and design principles that support the Archive Interface subsystem of the SSA. The Archive Interface is an extension of the core components of the Uplink subsystem and provides a set Web services to allow open access to the SSA data set. Web services technology provides a basis for searching the archive and retrieving data products. The Archive Interface provides three modes of access: a rich client, Web browser and scripts (via Web services). The rich client allows the user to perform complex queries and submit requests for data that is asynchronously downloaded to the local workstation. Asynchronous download is a critical feature given the large volume of a typical data set (on the order of 40 Gigabytes). For basic queries and retrieval of data the Web browser interface is provided. For advanced users scripting languages with Web services capabilities (i.e. Perl) can used to query and download data from the SSA. The archive interface subsystem is the primary means for searching and retrieving data from the SSA and is critical to the success of the Spitzer Space Telescope.