The growing popularity of software as a service (SaaS) as an alternative to traditional in-house systems represents one of the most interesting developments in the marketing software environment. Significant innovation in the marketing software field must come from outside the group of established vendors, however, since the industry continues to experience consolidation. SaaS vendors are best positioned to provide such innovation because they have the freedom to focus on specific functions rather than attempting to be all things to all customers. The greatest challenge for SaaS vendors involves integration across company systems. Convention vendors depend on the fact that difficulty with integration is the main reason their clients buy components within an integrated software suite. A weakness in the strategy of conventional vendors is that any changes required to facilitate the integration of products they obtain through acquisition frequently smooth the way for them to interact with external products as well. For SaaS vendors, an opposite approach is taken. These vendors understand that they would always be outside a client's core operating structure, so they have focused on simplifying integration with external systems. Recently, SaaS vendors have become more aggressive and opened their systems through APIs and web services connectors to make their internal components useful in other contexts.