Micro-frontend Architecture Guide. What Are Micro Frontends And When to Use Them?

In the software development world, the need to build complex web applications within short timelines has led to the rise of a concept known as micro frontends. This custom frontend development architecture can be traced back to the concept of microservices, where a complex application is broken down into smaller independent services that can be combined to create a fully functional application.  

In backend development, each microservice runs its own operating system process and unique database so they can communicate with each other over the network. A micro-frontend architecture is what you get when you apply this idea to frontend development. In this guide, we will explore what a micro-frontend architecture is and how it works. We will also explore micro frontend pros and cons, use cases, and best practices to follow. 

• A micro frontends architecture is one of the established software development practices that developers can leverage to meet the evolving requirements of modern web development.
• Micro frontends are an extension of the philosophy of the microservices architecture used by developers for building robust application backends. 
• This modular front-end development technique allows development teams to work independently on complex projects, leading to benefits like faster development cycles, better performance, and innovation. 

Understanding Micro-Frontend Architecture

The term “micro frontends” was coined relatively recently. The concept became popular within the past decade after it was first used by Michael Geers in 2016. Frontend developers have been leveraging this modular approach to frontend development to achieve efficiency and scalability.

Before diving fully into the nitty-gritty of micro frontends and how they compare to a frontend monolith, let’s begin this guide with a foundational understanding of this front-end development approach and how it fits into the broader software architecture landscape. If you seek more detailed information about the frontend in general, please read our comprehensive frontend development guide.

Definition and Purpose

The micro-frontend architecture is an approach to software development where the user interface of a website or application is broken down into smaller, manageable parts. Each micro frontend is a self-contained module that renders a specific section of the overall interface. 

Micro frontends are built and delivered independently (possibly by different teams in some cases). Each micro frontend has its own code repository, dependencies, automated testing suite, and delivery pipeline. This parallel development strategy is a faster and more efficient way to build frontends compared to the conventional monolithic frontend approach. 

Micro Frontends vs. Microservices

The micro-frontend architecture is essentially an extension of the microservices concept, which is a well-established development approach in backend development. In a microservices architecture, the backend of an application is divided into smaller, loosely coupled components known as services that can be independently developed and combined to form a whole. Each of these services is responsible for adding a specific function to the backend.

In both situations (backend and frontend microservices), the ultimate goal is to simplify development by breaking down a large, complex system into smaller ones that can be handled autonomously and combined later to create a solution that looks and works homogeneously. While the microservices architecture is used in building backend architectures, micro frontends apply to frontend development.

The Role of Team Autonomy in Micro Frontends

Autonomy is one of the core concepts and benefits of a micro-frontend approach to frontend development. With this approach, each module is a self-reliant system, which means it can work on its own and still function correctly.

Autonomy in micro frontends also applies to how the development team operates. The modular nature of micro frontends means different teams can work on a separate module of an entire project. Each team gets to select the most suitable technology stack for the micro frontend they’re building without being constrained by the choices being made by other teams.

This type of team autonomy leads to faster development cycles while also fostering innovation and efficiency. Developing and deploying modules independently also makes the entire system more resilient and easier to maintain compared to a monolithic application. 

How Micro Frontends Work

To fully understand how micro frontends work, it helps to compare them to the monolithic frontend architecture. In the conventional approach to frontend development, the entire frontend has a single codebase. This is a monolith that can become difficult to manage, scale, and update, especially for big projects or complex applications.

In micro frontends, the entire frontend is broken down into distinct, smaller applications, each one responsible for a specific section of the User Interface. For example, on an e-commerce website, you can have separate frontends to handle the shopping cart, product catalog, and user profile.

Each of these micro frontends can be developed and maintained by an autonomous team. Also, since they’re self-contained, they can be developed, tested, and deployed independently. An integration layer combines all of these individual modules within the same project into a unified and symmetric user interface to deliver a seamless user experience. 

Architectural Patterns in Micro Frontend Design

As defined above, a micro-frontend architecture consists of loosely coupled components and front-end technologies glued together to create a cohesive web page or application. To construct this type of system, you need to follow certain design patterns and implementation strategies. Some of these patterns are highlighted below.

Build-Time vs. Runtime Composition

Micro frontends combine multiple independent modules, each representing a unique feature or functionality. Module composition refers to the process of getting all of these components to work together to deliver the front-end functionalities. This can either be done at build time or at runtime. 

With the build-time composition, all the micro frontends are unified into a single application during the build phase of the frontend development process using a bundler or build tool like Webpack or Rollup. Each micro frontend becomes a library or module that the main host application calls or imports as needed. 

Build-time composition is generally simpler to deploy and offers great results in terms of performance. All the assets are bundled and optimized together during build, which means there are fewer network requests at runtime. As a result, frontends with this type of composition tend to load faster and deliver a more responsive and consistent user experience. 

On the flip side, this approach introduces some level of coupling between the micro frontends, which seems to be the opposite of what a micro-frontend architecture aims to achieve in the first place. To achieve build-time composition, the technologies used to build the integrated micro frontends also have to be compatible. 

On the other hand, runtime composition involves integrating micro frontends on the server before rendering the page or directly in the user’s browser. This is a truly decoupled and independent system, where each independent team gets complete freedom to build with their preferred technology without worrying too much about compatibility. The resulting frontend is also more resilient and less error-prone due to the complete isolation of the individual frontends.  

Expectedly, this composition approach is generally more complex as it requires more communication and advanced routing between the micro frontends. This can lead to significant performance overhead if not managed properly. 

Integration Techniques for Micro Frontends

Integration refers to the process of combining multiple frontends either on the server or in the client’s browser. This is achieved through different integration frameworks and techniques that dynamically load and render different frontend components into a cohesive application. Some of the main integration techniques that can be used in a micro-frontend architecture are listed below.

Web Components

The term web components refers to a standardized set of web technologies or browser APIs that developers can use to create custom and encapsulated HTML tags to be used on web pages or apps. Since one of the core principles of a micro-frontend architecture is to build modules that can be deployed independently, the encapsulated nature of these components makes them a valuable tool in this regard. 

In a web component, the internal structure, style, and behavior of the web element are contained within the component’s shadow DOM. This self-contained design prevents interference from other parts of the app. Each micro frontend includes its own components, which allows it to run without style clashes with other components. 

Iframes

The iframe integration technique involves embedding each micro frontend into its own iframe while the application acts as a container for all of them. This technique basically displays an HTML document inside another HTML document. 

This method enforces strict isolation between the micro frontends, with the SPA container coordinating communication between them. All the resources of the individual micro frontends don’t interfere with each other or those of the parent application. This technique is also relatively easy to implement. 

Despite all of its benefits, using Inline Frames to achieve strong isolation in micro frontends comes with a few downsides, including poor user experience, security, and performance issues. Search engines may also struggle to index content encapsulated within iframes effectively.

Module Federation

Module Federation is a feature in Webpack 5 introduced in 2020. This approach can help developers integrate micro-frontend components into one application while maintaining an average level of separation between the modules. 

With module federation, all the micro frontends are loaded into a shell application at run time without a build-time dependency. This approach allows you to change the configuration of your front end during runtime.  

Single-SPA

Single-SPA is a framework that aggregates multiple JavaScript micro frontends into one single-page application. The single SPA orchestrates the loading, mounting, and unmounting of each of these micro frontends within your application. Each micro frontend acts as an independent application and there are functions within the single SPA that determine when a particular micro frontend should be active or inactive. A single SPA makes all of these apps work together, ensuring that they don’t load until they’re needed.

Managing Routing and Navigation

In a conventional monolithic frontend codebase, a single router is responsible for rendering the appropriate components based on the app’s state. Things are a lot more complex with a micro-frontend architecture, where each frontend may have its own routing logic. 

To coordinate these disparate routes and deliver a consistent user experience, the software may use a centralized routine approach (where a single router controls navigation for all the micro frontends) or a decentralized routing approach (where each micro frontend manages its own routes).

There’s also the option of using a hybrid approach. In this case, the shell application handles top-level routing while more specific routes are dedicated to individual micro frontends.

State Management and Communication Strategies

Modules within a micro-frontend architecture need to be aware of each other’s states in order to exchange data or trigger specific actions. This is one of the most challenging aspects of adopting a micro-frontend architecture. You need to set these disparate frontends to communicate and interact without reintroducing tight coupling,

To achieve these, developers adopt a wide range of communication techniques to help micro frontends share states and communicate. Some of these communication protocols include pub-sub messaging, global stores, or event buses.

Using a global event bus (also known as custom browser events) is the most common way to achieve loosely coupled communication between micro frontends. With this approach, micro frontends can dispatch custom events and listen for events dispatched by other frontends to determine their state. 

An alternative approach is to use centralized state management through a shared global store. This is a single library that stores all the app states within the root application. This library is accessible to all micro frontends, providing a single source of truth for managing their shared state. Other communication and state management strategies that you can adopt include using URL parameters or browser storage. 

Essential Tools and Frameworks for Micro Frontends

A micro-frontend architecture requires certain tools or frontend frameworks to facilitate the development, integration, and deployment of micro-frontend solutions. These frameworks provide standard patterns or conventions that developers can adopt to build web apps with decoupled front-end modules. Below is a brief overview of the most popular tools and frameworks that facilitate a micro-frontend implementation. 

Single SPA Overview

Single SPA (Single Page Application) is a popular and mature micro-frontend framework that facilitates the development of multiple frontend apps in a way that allows them to coexist within a single application shell. 

A single SPA provides all the tools needed for the independent development, testing, and deployment of individual app modules with interaction and support for frontend frameworks such as React, Angular, and Vue. It also comes with built-in features like flexible routing for handling navigation between micro frontends. 

The extensive functionality and active community support offered by this Single SPA make it an ideal solution for building complex micro front-end architectures. It does come with a learning curve, and proper implementation is necessary to ensure optimal performance. 

Webpack Module Federation Explained

Module Federation is a popular micro-frontend framework perfect for developers who work with the Webpack ecosystem. The main feature of this framework is that it allows you to build micro frontends with minimal codependency. 

This approach allows micro frontends to share code and dependencies using dynamic module loading, which enhances flexibility while maintaining isolation between individual components. This solution also has features like code splitting and loading, which help to improve performance and scalability. 

Note that using module federation can be a bit complex since the configuration is quite advanced. Developers without sufficient knowledge of module bundling concepts will have a hard time adopting this solution. 

Nx for Micro Frontends

Nx is a powerful, open-source build tool designed primarily for managing mono repositories (a single control repository that contains the code for several projects). Nx supports a micro-frontend architecture, especially for projects leveraging the module federation integration techniques. This build tool provides a comprehensive set of tools and conventions required to streamline development and facilitate independent deployments.

Benefits of Micro Frontend Architecture

When implemented efficiently, a microfrontend architecture comes with several business benefits compared to traditional monolithic frontends, from rapid development to improved dependency management. If you’re still wondering whether or not this approach is right for you, here are some of the most notable micro frontend benefits in enterprise-scale applications.

Enhanced Scalability and Maintainability

With self-contained frontend components, developers get to spend less time on general maintenance to keep everything working properly. Bugs can be easily identified, isolated, and fixed without combing through the entire application codebase. Also, since you’re working with self-contained modules instead of a complete page or a monolithic application, it is possible to scale or upgrade only the necessary components that are experiencing increased demand with no effect on other frontends. 

Technology Agnosticism and Flexibility

The micro-frontend approach promotes greater flexibility, especially with the types of front-end technologies to use on your project. Multiple teams working on different micro frontends within the same app can select the most suitable and most efficient technology stacks for their specific use cases. 

Independent Development and Deployment

Micro frontends are decoupled and independent. This means each development team gets to build and deploy like they’re working on completely independent apps within a collaborative workshop. This autonomy gives room for innovation while also streamlining and speeding up development cycles. The new micro frontends created on a project are also reusable across multiple projects.

Better Team Collaboration

While breaking up your project into smaller code-based chunks might seem like it’s counter-collaboration, the opposite is actually the case. Micro frontends promote team ownership and reduce dependencies between teams. So, instead of waiting through layers of approvals and struggling to keep pace with many other teams, each team gets full control of their own end of the project and can make decisions quickly while adapting to changing project requirements. 

Challenges and Considerations of Micro Frontends

As the section above shows, there are several potential benefits to adopting a micro-frontend approach. However, there are also a few challenges that may hinder the progress and success of your project. Some of the common drawbacks and considerations to watch for when implementing a micro-frontend architecture include: 

Complexity in Integration and Deployment

Integrating and deploying multiple front-end components at once can be quite complex. It gets even trickier when each micro frontend is built with its own unique technology stack. You have to figure out how to manage the numerous libraries, frameworks, and dependencies within your project, which can be quite complex. 

Managing Performance and Bundle Sizes

Performance issues tend to arise when you combine different independent applications into one. Bundle sizes may grow too big, especially when you have duplicated dependencies, leading to latency issues. Performance issues can be mitigated by adopting effective load management strategies such as runtime composition, lazy loading, and server-side rendering. Rigorous front-end testing should also be carried out before final deployment to ensure all parts work as expected. 

Ensuring UI/UX Consistency Across Frontends

Another tricky aspect of trying to combine multiple frontends is how difficult it can be to ensure consistency in user interface design and experiences across all your frontends. As your teams work independently, it is important that you still maintain uniformity in the style, behavior, and performance of the individual components of your application. This can be achieved by adopting the same UI components and style guidelines for every team involved in the project. 

Real-World Applications and Examples of Micro Frontends

A micro-frontend approach is most commonly used for complex projects with multiple independent functions. Big enterprises with large teams may also benefit from the increased productivity that comes with this approach to frontend development. This section provides some real-world micro frontend examples:

How Leading Companies Use Micro Frontends

IKEA’s website was built with a micro-frontend architecture, which involved dividing the entire application into sections such as product pages, profile management, checkout process, etc., into separate projects that were developed independently. This demonstrates how useful this development approach can be in developing e-commerce platforms. Adopting micro frontends also made it easier to update and make changes to specific parts of the app or add new features based on tests and user feedback. 

Streaming platform Spotify also adopted a micro-frontend approach for the development of its web application. Different parts of the front end are integrated using Inline Frames (iFrames), with an event bus used for managing communication between different iFrames. This approach keeps the different parts of the application autonomous while still allowing the modules to communicate seamlessly. 

AWS-Based Micro Frontend Implementations

AWS offers a range of services that can be leveraged by developers and businesses to achieve independent development, deployment, and seamless integration of a micro-frontend system. Developers can use the AWS Developer tools to build and deploy applications to Amazon Simple Storage Service (S3) using Amazon CloudFront.

The release management (CI/CD pipelines) for each of the apps can use shared modular components stored in AWS CodeArtifact. This approach will help achieve consistency across all the micro apps within the parent web application.

Best Practices for Implementing Micro Frontends

To enjoy the full benefits of a micro-frontend architecture and avoid some of the potential downsides, you have to ensure that it is implemented properly. The following are essential tips and strategies that you should follow to ensure a successful micro frontend implementation. 

Define Clear Component and Team Boundaries

A true micro-frontend architecture is only achieved when the individual apps are fully decoupled. To ensure this, you need to clearly define the boundaries of each micro frontend module. Setting well-defined boundaries also gives each team a clear idea of which modules they’re responsible for within the project and reduces the chances of ending up with dependencies between modules. 

Use Shared Design Systems and Libraries

To keep the user interface design and experience consistent across different micro frontends. You need to use the same design systems and libraries across all the apps. This will help developers to achieve behavioral and visual consistency across the entire project. 

Establish Robust CI/CD Pipelines

Setting up a robust CI/CD pipeline for each micro front end ensures that each app undergoes automated testing and deployment. This simplifies the deployment process and also reduces the chances of errors occurring in this phase of your project. 

Monitor Performance and Optimize Continuously

To maintain the health and optimal performance of your frontend system, you need to implement tools for monitoring and logging performance. This provides full visibility into major performance metrics so you can proactively detect issues and rectify them accordingly. 

Conclusion: Is Micro-frontend Architecture Right for You?

A micro-frontend architecture is not just another buzzword in the frontend world. It is a great solution that can help businesses meet the demand for scalable and more adaptable web applications. This architecture can also be combined with other frontend development trends like frontend as a service and headless CMS to build more modern and efficient frontends. 

For developers working on large and complex applications or use cases that demand agile solutions capable of adapting quickly to changing requirements or evolving web component specifications, adopting a micro-frontend approach is highly recommended. By following best development practices, you can maximize the benefits of micro frontends and achieve optimal outcomes in your projects.

As you embark on your next software development journey, consider adopting a micro-frontend approach for your project with the help of an expert frontend development team like CrustLab. Contact us now to get started.