Software Architecture (SA) plays a critical role in developing and evolving cloud-based applications. We present a Reference Architecture (RA) for designing Cloud-based Tools as a service work SPACE (TSPACE) - a platform for provisioning chain of tools following the Software as a Service (SaaS) model. The TSPACE RA has been designed by leveraging well-known design principles and patterns and has been documented using a view-based approach. The RA has been presented in terms of its context, goals and design elements by describing the requirements, design tactics, and components of the RA. We evaluate the RA in terms of completeness and feasibility. Our proposed RA can provide valuable guidance and insights for designing and implementing concrete software architectures of TSPACE.