Service per team

pattern   service granularity  


A high performance development organization consist of multiple teams. Each team is long-lived, small (typically 5-9 people), loosely coupled, autonomous, and cross-functional. Conway’s law says an architecture mirrors the communication structure of the organization that builds it. Consequently, an organization consisting of loosely coupled teams needs a loosely coupled architecture.

One such loosely coupled architecture is the microservice architecture. It’s an application style that structures an application as a loosely coupled set of services. Decompose by Subdomain and Decompose by business capability are patterns for identifying services and organizing them around business functionality. But what’s the relationship between services and teams?

One approach is a shared ownership model where multiple teams to work on each service as necessary. For example, each team might be responsible for implementing features that span multiple services. On the one hand, this approach aligns teams with the user experience. But on the other hand, it increases the amount of coordination needed between the teams. Also, the lack of code ownership increases the risk of poor code quality.

A better approach, which increases team autonomy and loose coupling, is a code/service ownership model. The team, which is responsible for a business function/capability owns a code base, which they deploy as one of more services. As a result, the team can freely develop, test, deploy and scale its services. They primarily interact with other teams in order to negotiate APIs.

A team should ideally own just one service since that’s sufficient to ensure team autonomy and loose coupling and each additional service adds complexity and overhead. A team should only deploy its code as multiple services if it solves a tangible problem, such as significantly reducing lead time or improving scalability or fault tolerance.

Since a team must be small, its cognitive capacity is limited. In order for the team to be productive, its code base should be scoped to not exceed the team’s cognitive capacity. In other words, it must ‘fit’ in the team’s heads. As a result, there is an upper bound on the size and/or complexity of a service.


What’s the relationship between teams and services?


  • A team should be small, e.g. 5-9 people
  • A team should be autonomous and loosely coupled
  • The size and complexity of the team’s code base must not exceed the team’s cognitive capacity.
  • Finer-grained service decomposition improves -ilities including maintainability, testability, deployability
  • Finer-grained service decomposition adds complexity


Each service is owned by a team, which has sole responsibility for making changes. Ideally each team has only one service:

Each team is responsible for one or more business functions (e.g. business capabilities). A team owns (has sole responsibility for changing) a code base consisting of one or more modules. Its code base is sized so as to not exceed the cognitive capacity of team. The team deploys its code as one or more services. A team should have exactly one service unless there is a proven need to have multiple services.

Resulting context

This pattern has the following benefits:

  • Enables each team to be autonomous and work with minimal coordination with other teams
  • Enables the teams to be loosely coupled
  • Achieves team autonomy and loose coupling with the minimum number of services
  • Improves code quality due to long term code ownership

This pattern has the following drawbacks:

  • Teams are not necessarily aligned with end user features
  • Implementing features that span services is more complicated and requires teams to collaborate

pattern   service granularity  

Copyright © 2024 Chris Richardson • All rights reserved • Supported by Kong.

About is brought to you by Chris Richardson. Experienced software architect, author of POJOs in Action, the creator of the original, and the author of Microservices patterns.

New workshop: Architecting for fast, sustainable flow

Enabling DevOps and Team Topologies thru architecture

DevOps and Team topologies are vital for delivering the fast flow of changes that modern businesses need.

But they are insufficient. You also need an application architecture that supports fast, sustainable flow.

Learn more and register for my September 2024 online workshops....


I help organizations improve agility and competitiveness through better software architecture.

Learn more about my consulting engagements, and training workshops.

LEARN about microservices

Chris offers numerous other resources for learning the microservice architecture.

Get the book: Microservices Patterns

Read Chris Richardson's book:

Example microservices applications

Want to see an example? Check out Chris Richardson's example applications. See code

Virtual bootcamp: Distributed data patterns in a microservice architecture

My virtual bootcamp, distributed data patterns in a microservice architecture, is now open for enrollment!

It covers the key distributed data management patterns including Saga, API Composition, and CQRS.

It consists of video lectures, code labs, and a weekly ask-me-anything video conference repeated in multiple timezones.

The regular price is $395/person but use coupon WURMXAJV to sign up for $95 (valid until July 19th, 2024). There are deeper discounts for buying multiple seats.

Learn more

Learn how to create a service template and microservice chassis

Take a look at my Manning LiveProject that teaches you how to develop a service template and microservice chassis.

Signup for the newsletter

BUILD microservices

Ready to start using the microservice architecture?

Consulting services

Engage Chris to create a microservices adoption roadmap and help you define your microservice architecture,

The Eventuate platform

Use the platform to tackle distributed data management challenges in your microservices architecture.

Eventuate is Chris's latest startup. It makes it easy to use the Saga pattern to manage transactions and the CQRS pattern to implement queries.

Join the microservices google group