Difference between Stateful vs Stateless Architectures? When to use?

Differences between stateful and stateless architectures and how they impact system design and scalability.

Hello guys, difference between stateless and stateful architecture is a common interview questions to senior developer which is also a great opportunity to impress your interviewer.

Ever since I started designing systems or giving my input, my focus was always to go for stateless as much as possible and only choose stateful if there is no other option to meet certain business requirements.

But why stateless? because managing state brings a lot of problems and stateless architecture are easier to create, maintain and scale.

If you are new here, In the past, I have talked about common system design questions like Rate Limiter, Database Scaling, API Gateway vs Load Balancer and Horizontal vs Vertical Scaling, Forward proxy vs reverse proxy as well common System Design problems and concepts like Single Point Failure, and in this article we will talk about Stateful and Stateless architectures, two important topics from scalability and system avaibility point of view.

For this article, I have teamed up with Hayk and we'll dive into the fundamental concepts of what is stateless and stateful architecture, and provide practical insights to help you make informed decisions about your software architecture.

By the way, if you are preparing for System design interviews and want to learn System Design in depth then you can also checkout sites like ByteByteGo, Design Guru, Exponent, Educative, Codemia.io, and Udemy which have many great System design courses

What is Stateful?