19 Microservices Patterns for System Design Interviews

Disclosure: This post includes affiliate links; I may receive compensation if you purchase products or services from the different links provided in this article.

image_credit - ByteByteGo

Hello friends, if you are preparing for system design interviews, then it makes sense to prepare for Microservices design patterns as well, not just to do well on interviews or make your architecture more robust, but also to understand existing projects.

Microservices patterns like Circuit Breaker, API Gateway, Saga, and Event Sourcing are tried and tested solutions to common Microservices Problems.

These patterns address common challenges in microservices architectures like scalability, fault tolerance, and data consistency.

In the past, I have talked about common system design questions like API Gateway vs Load Balancer and Horizontal vs Vertical Scaling, Forward proxy vs reverse proxy as well common System Design problems and in this article I am going to share 24 key Microservices design patterns that are essential knowledge for technical interviews.

They are also one of the essential System design topics for interview, and you must prepare them well.

Many companies use microservices, so understanding these patterns shows you're up-to-date with current trends. Knowing when and how to apply these patterns also demonstrates your ability to solve complex distributed system problems.

These patterns often involve trade-offs, allowing you to showcase your analytical thinking. Interviewers often present scenarios where these patterns are relevant solutions.

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 and a System design interview template like this which you can use to answer any System Design question.

If you need more choices, you can also see this list of best System Design courses, books, and websites

P.S. Keep reading until the end. I have a free bonus for you.

So, what are we waiting for? Let's jump right into it

19 Microservices Design Patterns for System Design Interviews

Microservices architecture is a design approach that structures an application as a collection of loosely coupled services.

To build scalable, maintainable, and resilient microservices-based systems, various patterns have emerged.

Here are essential microservices patterns you can use in your project, and also remember for system design interviews.

1. Service Registry

Since there are many microservices in a microservice architecture, they need to discover and communicate with each other.

A Service Registry, such as Netflix Eureka or Consul, acts as a centralized directory where services can register themselves and discover others.

Here is what it looks like:

2. API Gateway

An API Gateway serves as a single entry point for client applications, aggregating multiple microservices into a unified API.

It handles requests, routing them to the appropriate services, and may perform tasks like authentication, authorization, and load balancing.

Here is what API Gateway looks like:

3. Circuit Breaker

Inspired by electrical circuit breakers, this pattern prevents a microservice failure from cascading to other services. The Circuit breaker pattern monitors for failures and, if a threshold is crossed, opens the circuit, preventing further requests.

This helps with graceful degradation and fault tolerance, and it's essential in a Microservice architecture to prevent a total shutdown of your services.

Here is an example of Netflix Hysrix as a circuit breaker:

4. Bulkhead

In a microservices system, isolating failures is crucial. The Bulkhead pattern involves separating components or services to contain failures.

For example, thread pools or separate databases for different services can be used to prevent a failure in one part of the system from affecting others.

Here is a diagram showing the Bulkhead pattern in Microservices architecture:

5. Saga Pattern

This pattern is used for managing distributed transactions. The Saga pattern breaks down a long-running business transaction into a series of smaller, independent transactions.

Each microservice involved in the saga handles its own transaction and publishes events to trigger subsequent actions.

Here is how Saga Pattern looks in action:

6. Event Sourcing

This is another popular pattern which is used heavily in high frequently low latency applications.

In this pattern, instead of storing only the current state, Event Sourcing involves storing a sequence of events that led to the current state.

This pattern provides a reliable audit trail and allows for rebuilding the system state at any point in time.

Here is how Event Sourcing looks in action:

7. Command Query Responsibility Segregation (CQRS)

CQRS Pattern separates the read and write sides of an application. It uses different models for updating information (commands) and reading information (queries).

This pattern can improve scalability, as read and write operations have different optimization requirements.

Here is a nice diagram that shows the CQRS pattern:

8. Data Sharding

Database sharing pattern is used to distribute the database load and avoid bottlenecks. Data Sharding involves partitioning data across multiple databases or database instances.

In this pattern, each microservice may handle a subset of data or specific types of requests.

Here is how database sharding looks, credit - Design Guru

9. Polyglot Persistence

Different microservices may have different data storage needs. Polyglot Persistence allows using multiple database technologies based on the requirements of each microservice, optimizing for data storage, retrieval, and query capabilities.

Here is a nice diagram that shows Polyglot persistence in Azure :

10. Retry

In Microservice architecture, when a transient failure occurs, the Retry pattern involves retrying the operation instead of immediately failing.

It can be applied at various levels, such as service-to-service communication or database interactions.

Here is a nice diagram from ByteByteGo, a great place for system design learning, which shows the Retry pattern in Microservices:

12. Sidecar

The Sidecar pattern involves attaching a helper service (the sidecar) to the main microservice to provide additional functionalities such as logging, security, or communication with external services.

This allows the main service to focus on its core functionality.

Here is what a Sidecar pattern looks like:

13. Backends for Frontends (BFF)

Also known as BFF, this pattern is useful when dealing with multiple client types (e.g., web, mobile). The BFF pattern involves creating separate backend services tailored for each type of client.

This allows for optimized and specialized APIs for each client.

Here is what a Backends for Frontends (BFF) pattern looks like:

14. Shadow Deployment

The Shadow Deployment pattern involves routing a copy (shadow) of production traffic to a new microservice version without affecting the actual user experience.

This is one of the popular deployment strategies, and it helps validate the new version's performance and correctness.

Here is what shadow deployment looks like

15. Consumer-Driven Contracts

In a microservices ecosystem, multiple services often interact with one another. The Consumer-Driven Contracts pattern involves consumers specifying their expectations from producers, allowing for more robust and coordinated changes.

Here is a nice diagram that explains Consumer Driven contracts

16. Smart Endpoints, Dumb Pipes

This pattern advocates for placing business logic in microservices (smart endpoints) rather than relying on complex middleware. The communication infrastructure (pipes) should be simple and handle only message routing.

17. Database per Service

This is another popular Microservices pattern where each microservice has its own database, and services communicate through well-defined APIs.

Database per Service pattern provides isolation but also requires careful consideration of data consistency and integrity.

Here is how this pattern looks:

18. Async Messaging

Instead of synchronous communication between microservices, the Async Messaging pattern involves using message queues to facilitate asynchronous communication. This can improve system responsiveness and scalability.

Here is a nice diagram that shows the difference between sync and async messaging

19. Stateless Services

Designing microservices to be stateless simplifies scalability and resilience. Each service processes a request independently, without relying on stored state, making it easier to scale horizontally.

Here is a nice diagram which shows the difference between Stateless Services and Stateful Services

System Design Interviews Resources

And, here is my curated list of best system design books, online courses, and practice websites which you can check to better prepare for System design interviews. Most of these courses also answer questions I have shared here.

DesignGuru's Grokking System Design Course: An interactive learning platform with hands-on exercises and real-world scenarios to strengthen your system design skills.
Codemia.io: This is one of the best places to practice System design problems for interviews online. It has more than 120+ System design problems, many of which are free and also a proper structure to solve them.
Exponent: A specialized site for interview prep, especially for FAANG companies like Amazon and Google. They also have a great system design course and many other materials which can help you crack FAANG interviews.
"Designing Data-Intensive Applications" by Martin Kleppmann: A comprehensive guide that covers the principles and practices for designing scalable and reliable systems.
LeetCode System Design Tag: LeetCode is a popular platform for technical interview preparation. The System Design tag on LeetCode includes a variety of questions to practice.
"System Design Primer" on GitHub: A curated list of resources, including articles, books, and videos, to help you prepare for system design interviews.
Educative's System Design Course: An interactive learning platform with hands-on exercises and real-world scenarios to strengthen your system design skills.
High Scalability Blog: A blog that features articles and case studies on the architecture of high-traffic websites and scalable systems.
YouTube Channels: Check out channels like "Gaurav Sen" and "Tech Dummies" for insightful videos on system design concepts and interview preparation.
ByteByteGo: A live book and course by Alex Xu for System design interview preparation. It contains all the content of the System Design Interview book volumes 1 and 2, and will be updated with volume 3 which is coming soon.
"System Design Interview" by Alex Xu: This book provides an in-depth exploration of system design concepts, strategies, and interview preparation tips.

image_credit - ByteByteGo

That's all about the common Microservice patterns and concepts a developer should know. These microservices patterns help address various challenges associated with building and maintaining distributed systems, providing solutions for communication, fault tolerance, data management, and scalability.

When designing microservices architectures, combining these patterns judiciously can lead to a robust and resilient system.

These additional microservices patterns, when applied thoughtfully, contribute to building resilient, scalable, and maintainable distributed systems.

The choice of patterns depends on the specific requirements and challenges faced during the design and implementation of microservices architectures.

Bonus

As promised, here is the bonus for you, a free book. I just found a new free book to learn Distributed System Design, you can also read it here on Microsoft --- https://info.microsoft.com/rs/157-GQE-382/images/EN-CNTNT-eBook-DesigningDistributedSystems.pdf

Top 15 Courses to Learn System Design and Software Architecture in 2025 - Best of Lot

Software design or System design is one of the tricky concepts to master. You can quickly learn a programming language like Java or Python, but creating software using that programming language is a totally different thing. That's where software design and coding skills come to the rescue. It's actually an art to structure your program, design your modules, specify boundaries and interactions with other parts of the system so that they are easier to read, maintain, and flexible to change. It's one of the most essential skills for a software developer but often gets ignored. If you look for an online course to learn Software design and architecture, you won't find many, forget about good ones.

Top 5 Online Courses to learn Design Patterns in JavaScript in 2025 - Best of Lot

If you are a JavaScript web developer and want to learn design patterns to further improve your coding and development skills and looking for the best design pattern courses in JavaScript, then you have come to the right place. Earlier, I have shared the best JavaScript courses for beginners. Today, I will share the best courses to learn Design Patterns in JavaScript from Udemy, Pluralsight, Udacity, and LinkedIn Learning. These are truly great online courses that you can join to learn this valuable skill and become a better JavaScript developer.

Top 5 Free Courses to learn Design Patterns in Java and TypeScript in 2025 - Best of Lot

No matter how good or experienced a programmer is, they will run across issues when programming. As a number of problems arise in code, you may see some commonalities, and when you try to address them, you may detect certain patterns. The term "Design pattern" comes into play here. Design patterns, in basic words, are tried-and-true solutions to common programming problems. For instance, creational design patterns address object creation issues.

Top 5 Object Oriented Analysis and Design Interview Questions for Programmers, Software Engineers

Testing the design skill of a candidate is quite common in programming job interviews. Questions like, how do you design a vending machine or a traffic control system are very popular in object-oriented programming language interviews, like Java and C++. Designing a software System requires good experience and knowledge of tools of object-oriented design and analysis. You should not only be good at OOP fundamentals like Abstraction, Inheritance, Polymorphism, Encapsulation, Coupling, Cohesion, Association, Aggregation, or Composition but also on several crucial object-oriented design principles like SOLID Principles of Object-Oriented Design, which is the building block for writing flexible and maintainable code.

Top 20 System and Software Design Interview Questions for Java Programmers (2025)

System design questions are an important part of programming job interviews and if you want to do well, you must prepare this topic. In the past, when I shared my list of programming interview questions, I have shared a couple of System design questions but my readers kept asking me for more questions, as it is a hard topic to master and more and more practice is needed. I had my own list of questions that I have collected from various interviews with friends and colleagues but I needed more questions for this article and my own preparation then I stumbled upon the Grokking System Design Interview course. It's an excellent resource because it not only gives you a lot of System design question but also provide all the knowledge and tools you need to solve those questions.

Top 7 Courses to Learn Design Patterns in Java for Experienced Programmers in 2025 - Best of Lot

Hello Java programmers, if you want to learn Design patterns in 2025 and looking for the best resources like books, tutorials, and online courses then you have come to the right place. Earlier, I have shared the best design pattern books, interview questions, and design pattern tutorials and in this article, I am going to share the best design pattern courses for Java developers. A design pattern is the tried and tested solution of classical software problems which is common during software development. Knowing design pattern not only help you to solve those problems quickly but also encouraged you to use tried and tested solution, thus overall improving the quality of the software application you are building.

How to create a thread-safe Singleton in Java using Enum [Example]

Hello guys, the Singleton pattern in Java is used to create a Singleton class that is accessed by a single instance though out the Java program life cycle. Singleton is one of the old but very useful design patterns and used in several core Java libraries including Java Development Kit (JDK); java.lang.Runtime is an example of a Singleton pattern in Java. This class represents a single instance of Java environment running as JVM and provides several utility methods to query important details about runtime like a number of available processors, Java heap memory, etc.

Aggregator Design Pattern In Java Microservices with Examples

The Aggregator design pattern in Microservice architecture is a design pattern used to compose a complex service by aggregating the responses of multiple independent microservices. It's also one of the essential Microservices Design patterns along with SAGA, CQRS, and Event Sourcing. This pattern is proper when a client request requires data or functionality distributed across multiple microservices. It can improve the performance and scalability of the system by allowing each microservice to focus on a specific task and reducing the workload of a single microservice. In this article, we will discuss how the Aggregator Microservice Pattern can be implemented in Java using various approaches, such as asynchronous communication, synchronous communication, or a combination of both. We will also provide examples of code to illustrate each approach.

What is API Gateway Design Pattern in Microservices? With Examples

Hello guys, API Gateway Design Pattern is a pattern that has emerged as a popular solution for managing APIs in a microservices architecture. As the number of services in the architecture increases, it becomes challenging to manage the APIs and handle requests from external clients. To address this challenge, API Gateway Design Pattern provides a single entry point for all the APIs in a microservices architecture. In the past, I have shared several Microservices design patterns like e Event Sourcing, SAGA, Database Per Microservices, CQRS, API Gateway, and also shared best practices to design Microservices and in this article, I am going to talk about the API Gateway Design Pattern, and how you can implement in Java using Spring Cloud Framework (Spring Cloud Gateway).

Asynchronous Messaging In Java? JMS, Kafka, and RabbitMQ Examples Tutorials

Hello fellow Java developers? Are you tired of those pesky synchronous messages clogging up your code like old grease in a drainpipe? Fear not, because today we're talking about asynchronous messaging in Java – the ultimate solution for decoupling your processes and improving the performance of your applications. But before we dive into the juicy details, let's start with the basics. What is Asynchronous Messaging? Asynchronous messaging is a method of communication between two or more processes like Microservices, where the sender sends a message and doesn't wait for a response before continuing with its own tasks. This is in contrast to synchronous messaging, where the sender must wait for a response before continuing.

What is CQRS Pattern in Java Microservices? Command Query Responsibility Segregation Example Tutorial

Hello guys, if you are wondering what is CQRS pattern and when and how to use it in your Microservices then you have come to the right place. CQRS is one of the 10 essential Microservice pattern and can be used when your application is either read heavy or write heavy and reading and writing requirement are very different. It aims to separate your app into two parts, command part which writes data and query part which read data and that's how it allows you to develop, scale and optimize them separately. It's also one of the popular Microservices Questions and if you are preparing for interviews, you should prepare this pattern as well. Earlier, I have explained SAGA Pattern and Database Per Microservice pattern and in this article I will explain CQRS pattern, when to use it and what problem does it solve.

SAGA Design Pattern In Java Microservices with Example

Hello guys, if you want to learn about SAGA Microservice design pattern then you have come to the right place. SAGA is one of the 10 essential Microservice Design Patterns I have shared earlier and it solve a critical problem related to distributed transaction. But, before we get to the different examples that will teach you all about SAGA microservice design patterns in Java, let me tell you a bit more about what it really is. A microservice-based application is basically a distributed system. The overall system consists of multiple minor services, which provide the overall application functionality. This architectural style offers numerous benefits as well as several limitations. SAGA Pattern is also one of the popular Microservice interview question and if you are going for interview, it make sense to learn and understand this design pattern in depth.

What is Event Sourcing Design Pattern in Java Microservices? Example

Hello Java programmers, if you are tired of constantly trying to keep track of your application's current state using a traditional relational database then the Event Sourcing pattern might be just what you need. Event Sourcing is a popular pattern in Microservice architecture that allows services to persist and query the state of an application using a sequence of events instead of storing the current state. This pattern has gained popularity because it helps to build complex systems with a clear audit trail and support for long-term scalability. By storing a sequence of events, rather than just the latest state, developers can reconstruct the application state at any point in time, even after failures or bugs. It's also one of the 10 essential Microservice patterns I have shared earlier and it's one of the top 3 along with Saga and CQRS patterns which we have seen in my earlier articles.

Chain of Responsibility Pattern in Java? Example Tutorial

Hello guys, if you have been doing Java development then you must have come across design pattern, tried and tested solution of common software problem. In the past, we have looked at several popular Object Oriented Design Patterns in Java like Adapter, Decorator, State, Strategy, Template, Composite, Command, Observer, Factory, Builder, Visitor etc, and today I am going to talk about Chain of Responsibility design pattern in Java. The Chained or Chain of Responsibility Pattern is a design pattern that allows a request to be passed along a chain of objects until it is handled by one of the objects in the chain. This pattern is helpful for situations where it is not known in advance which object in the chain should handle the request, or where the request needs to be handled by multiple objects in the chain.

Difference between Proxy and Decorator Pattern in Java

Hello guys, if you have gone through a couple of Java Developer interview then you may seen this question about Proxy and Decorator Pattern in Java. Earlier, I have share 18 Design Pattern questions and today, I am going to answer this tricky design pattern questions from Java interviews. I was first asked about difference between Proxy and Design Pattern in Java a couple of years back when I was interviewing for Senior Java developer interview on a big investment Bank and I wasn't able to impress interviewer with my answer, so I decided to learn more and this article is the result of that research. Though both Proxy and Decorator pattern looks very similar to each other structurally, there are some key differences between them like what problem them solve and how they are used in Java application.

Visitor Design Patterns In Java Examples Tutorial

Hello guys, if you want to learn Visitor design pattern in Java then you have come to the right place. Earlier, I have covered many design patterns like Decorator, Strategy, State, Composite, Adapter, Command, Template, Factory, Observer and even few Microservice patterns like SAGA and Database per service and in this article, I will talk about Visitor Design Pattern and how to implement in Java. You will learn things like what is Visitor design pattern, what problem it solves, what are pros and cons of Visitor design pattern, when to use Visitor pattern as well as any alternatives of Visitor Pattern in Java. I will also show you a real world example of Visitor design pattern, but, before we get to the 5 best examples that will teach you all about design patterns in Java, let me tell you a little bit more about what it really is.

Composite Design Pattern Example in Java and Object Oriented Programming

Hello guys, if you are wondering how to use Composite design pattern in Java then you are at the right place. Composite design pattern is another object oriented design pattern introduced by Gang of Four in there timeless classic book Design pattern : Elements of Reusable software. Composite pattern as name suggest is used to compose similar things together, like similar objects. It implements an interface and also contains other objects which implements the same interface, also known as containee. One of the best example of Composite pattern from Java standard library is Swing's container classes e.g. Panel, which not only are Components by themselves, but also contains other components like JButton, Label, JTable etc.

5 Ways to implement Singleton Design Pattern in Java? Examples

Hello guys, While Singleton is anti pattern nowadays and dependency injection is better choice as it helps unit testing, its good to know about Singleton pattern, especially if you are in the business of maintaining large and old code base. This article introduces the singleton design pattern and its 5 implementation variations in Java. You will learn different ways to implement a singleton pattern and understand the challenges of creating a singleton class, like thread-safety issues and serialization issues.

Pages