What is Scalable SaaS Architecture?

Scalable SaaS architecture is the design of a SaaS application and its infrastructure that keeps performance steady when traffic demands change, using vertical scaling (more capacity per server) and horizontal scaling (more servers).

Demand can change fast: Zoom went from about 10 million daily meeting participants at the end of December 2019 to more than 200 million in March 2020.

A scalable architecture matters because, as your user base grows, you must adapt to their new requirements. How you adapt to market demands and other adjustments depends on your SaaS architecture implementation.

Here are some of the reasons why you need to consider your SaaS architecture:

• Growth: Scalable SaaS architectures should facilitate growth as your product becomes more established, but they should not sacrifice performance. Reliability is also a crucial consideration here.
• Avoiding Churn: SaaS architectures need to have the capacity to manage more customers; use scalable systems to avoid overwhelm and lower churn rates.
• Performance: SaaS infrastructures should not perform worse during peak periods, nor should they use more resources than required (and exacerbate costs) during downtime; scalable infrastructures let you fine-tune resourcing for performance purposes.
• Agility: Regardless of your industry, customer behaviors and technological demands might change. As a result, you must have a SaaS infrastructure that can scale according to these needs; you want to limit the amount of technical input.

Consider these factors when determining whether you’ll use a scalable SaaS infrastructure. They should also influence your decision to partner with certain software providers.

Backend scalability starts with caching mechanisms. Meanwhile, load balancing is essential for even cross-server traffic distribution, which should prevent bottlenecks.

Other things to consider are:

• Microservices architectures break large apps into small services.
• Asynchronous processing is essential to handle tasks independently.
• You should add new servers via horizontal scaling.

Understanding customer lifetime value and other metrics is vital for SaaS backend scaling. You also need to think about modular architecture and how you balance loads across servers.

Two other factors are a specific growth plan and the tenancy model: in a multi-tenant design, customers share one application and infrastructure while their data stays isolated. Event-triggered tasks can also run as backend functions that the cloud provider scales automatically.

Pros and cons to think about are:

Pros:

• Scale up or down, depending on your current traffic.
• You should use microservices architecture when updating features, for bug-fixing, and for additional functions.
• Independent deployments might help you launch quicker, but only if done effectively.

Cons: 

• You must think about your overhead and plan in advance.
• Consider the impact on latency and whether you need to add anything else for app performance.
• You’ll need to allocate energy to solving issues efficiently.

Potential things to think about when scaling cloud infrastructure are:

• Flexibility: Prepare for fluctuations in traffic and consider how many resources you need. Surges can be steep: Zoom’s daily meeting participants rose from about 10 million at the end of December 2019 to more than 200 million in March 2020 (Zoom, April 2020).
• Scalability: You need to have the ability to scale depending on traffic, and to shrink again when it drops, which is where scaling and elasticity differ.
• Complexity: Understand the complexities of scaling cloud infrastructure if you’re a bigger organization; defining it as Infrastructure as Code (IaC) keeps environments consistent.
• Cost: You must be careful with how you use cloud infrastructure so that it doesn’t get expensive; monitor resource use, one of the key metrics for scaling operations.