Serverless Functions: What are they and when to use them

What is Serverless and should you use it when building microservices?

3 Min Read

Serverless functions have revolutionized the way developers build and deploy applications in the cloud. By eliminating the need to manage server infrastructure, serverless functions enable a greater focus on code and functionality. This comprehensive guide explores the what, when, why, and how of serverless functions, along with an examination of their pros, cons, and suitable alternatives.

What Are Serverless Functions?

Serverless functions, or Function as a Service (FaaS), allow developers to execute code in response to events without managing underlying servers. They are stateless, event-driven, and automatically scale with demand.

When and Why to Use Serverless Functions?


  • Rapid Prototyping: Quick deployment without server setup.
  • Event-Driven Scenarios: Such as reacting to file uploads, database changes, etc.
  • Variable Workloads: Managing spikes or drops in traffic.
  • Microservices Architecture: Building independent, scalable services.


  • Cost Efficiency: Pay only for execution time.
  • Ease of Management: No need to handle servers.
  • Automatic Scaling: Scales with demand.
  • Rapid Development: Focus on coding, not infrastructure.

How Do Serverless Functions Change Application Design?

Using serverless functions often requires a shift in application design:

  • State Management: Being stateless, serverless functions require different strategies for managing state.
  • Shorter Running Time: They are designed for short, reactive tasks. This means it is difficult to design for business logic requiring long-running tasks.
  • Event-Driven Architecture: The architecture revolves around reacting to events.
  • Integration with Other Services: Often used with other cloud services for full functionality.

Pros and Cons on Serverless Functions


  • Cost-Effective: Pay for usage.
  • Rapid Deployment: Less focus on infrastructure.
  • Scalability: Automatic scaling.
  • Integration: Easy integration with other cloud services.


  • Cold Starts: Initial latency in execution.
  • State Management: Challenges in managing state.
  • Limited Execution Time: Not suitable for long-running processes.
  • Vendor Lock-in: Potential reliance on specific cloud providers.

What Are Step Functions?

Step functions coordinate the components of distributed applications and microservices. They provide a way to sequence serverless functions and other services, creating visual workflows to build applications quickly.

What are Lambda Functions?

Serverless Lambda functions (an AWS offering) provide an environment to run code in various languages in reaction to triggers. They offer all the benefits of serverless architecture, enabling scalable, event-driven, cost-effective applications.

Limitations and a Future-Safe Alternative with Encore

While serverless functions offer significant advantages, there are limitations, such as challenges with long-running tasks, state management, and cold starts.

Encore provides a solution to unlock more flexible deployment models. With Encore, you can use infrastructure that can be both serverless and otherwise, even using Kubernetes. This ensures:

  • Flexibility: Choose between serverless or traditional deployments.
  • Simplicity: Infrastructure setup and configuration is automated by Encore's platform, and deploys to your own cloud account in AWS and GCP.
  • Scalability: Scale according to needs.
  • Avoidance of Vendor Lock-in: Use various cloud providers without changing application code.
  • Long-term Security: Future-safe approach with adaptable infrastructure.


Serverless functions mark a significant advancement in cloud computing, enabling scalable, event-driven applications with cost efficiency. While there are notable pros and cons, understanding your specific needs and constraints will guide the most effective use of serverless functions. Integrating technologies like Encore can provide an even more flexible, adaptable, and future-proof approach to modern development.

Ready to escape the hamster wheel?

Encore is Backend Development Platform purpose-built for creating event-driven and distributed systems — from developing locally to scaling in your cloud on AWS/GCP.