Definition: Architectural design where servers store no session data between requests, enabling effective horizontal scaling and fault tolerance.
— Source: NERVICO, Product Development Consultancy
What is Stateless Architecture
Stateless architecture is a design pattern where servers store no session state between requests. Every request that reaches a server contains all the information needed to be processed completely and independently, without relying on data stored in memory from previous requests. If the server needs to access session data, it is stored in a shared external service such as Redis, a database, or a JWT token.
How it works
In a stateless architecture, when a user logs in, authentication information is not saved in the server’s memory. Instead, a token (such as a JWT) is generated, sent to the client, and included in every subsequent request. Alternatively, session data is stored in a shared external store like Redis or DynamoDB, accessible from any server instance. This way, any server in the pool can serve any request from any user regardless of which server handled previous requests. There is no affinity between a user and a specific server.
Why it matters
Stateless architecture is a prerequisite for effective horizontal scaling. If servers store state in memory, adding new servers does not distribute load correctly because a user’s requests must always be directed to the same server (sticky sessions). This creates bottlenecks and single points of failure. With stateless servers, the load balancer can send each request to any available instance, instances can be freely created and destroyed via auto-scaling, and a server failure does not lose session data for any user.
Practical example
A project management web application migrates from an architecture with in-memory server sessions to stateless. Previously, it used sticky sessions on the load balancer so each user always reached the same server. When a server failed, all users on that server lost their session. After the migration, sessions are stored in Redis and authentication is handled with JWT tokens. The team removes sticky sessions, configures auto-scaling from 2 to 20 instances based on load, and the loss of any individual instance is transparent to users.
Related terms
- Horizontal Scaling - Scalability strategy that stateless architecture enables effectively
- Load Balancer - Component that freely distributes requests across stateless servers
Last updated: February 2026