When architecting a SaaS product, the software architecture profoundly impacts scalability, maintenance, and the overall customer experience. Over the years, some preferred architectures have emerged that balance these factors in different ways.

One popular approach is a multi-tenant architecture where customers share common infrastructure and code, but their data remains segregated. This minimizes overhead for the SaaS provider. However, multi-tenancy comes with challenges like ensuring adequate tenant isolation.

On the other end of the spectrum lies a single-instance, multi-database model. Here, each client gets their own individual instance and database. This simplifies customization and maximizes tenant isolation. However additional infrastructure and ops effort is required to manage many software and database instances.

A hybrid approach is the multi-instance, multi-tenant model. This combines the customizability of multiple instances with some resource pooling via multi-tenancy. Complexity does increase, but it can offer the right balance of customization and efficiency.

Serverless architectures are also emerging as an approach tailored for SaaS scalability and cost efficiency, though adoption is still in the early stages.

Choosing the right SaaS architecture is all about evaluating trade-offs between operational overhead, customizability, and tenant isolation. As SaaS consultants, we always dive deep into these considerations when advising clients on architecting, developing, and scaling SaaS products. Let us know if you need any guidance!