Micro frontend architecture 101: what is it, when to use it and how to migrate your existing monolithic app in 9 steps

Just as microservices revolutionized backend architecture, micro frontend architecture is already redefining how we build and scale user interfaces. This fresh architectural approach helps companies deliver tangible results where it counts: cutting software development and maintenance costs.

A well executed strategy can help companies with old, legacy solutions modernize them gradually, component by component, without the need to build an entirely new app at once.

The micro frontend architecture decomposes UIs into smaller parts, allowing for simultaneous development. This can help companies reduce the effort required to bring new functionalities to the market by as much as 50%!

In this article, we delve into the world of micro frontends, exploring their advantages and disadvantages, and the scenarios in which they will work as well as those where they won’t work. Finally, we outline the process for migrating from a monolithic frontend architecture to micro frontends, step by step.

Let’s get started with some definitions.

What is a micro frontend?

A micro frontend is a self-contained, independent application module (or an application itself) responsible for a specific part of the user interface (UI) in a web application.

The concept emerged to extend the microservices architecture on the backend, which focuses on breaking down a monolithic application into smaller, easily manageable services. Similarly, in a micro frontend architecture, the UI is divided into smaller components or modules that can be developed, deployed, and maintained independently. Each module is typically responsible for a unique business function.

Micro frontend architecture was created to address challenges of large and complex web applications, such as coordination between development teams, versioning issues, and the need for frequent updates. By breaking the frontend into smaller parts, each managed by its own team, the micro frontend framework promotes modularity, scalability, and flexibility in technology choices.

Micro frontends are:

• decomposed: the user interface is divided into smaller, granular pieces instead of forming a monolith,
• independent: each micro frontend operates as an independent unit, having its own codebase, data, and logic,
• tech-agnostic: different micro frontends can be developed using different technologies, programming languages, and frameworks,
• deployable separately: updates or changes to one module do not necessitate the redeployment of the entire application,
• loosely coupled: micro frontends communicate through well-defined interfaces or APIs, which means that changes in one module do not create unintended effects in others.
• customizable: micro frontend apps typically allow to offer personalized user experiences – the different modules can be tailored to specific user requirements,
• updated incrementally: as changes are isolated to specific modules, updates can be released incrementally, reducing the risk of introducing bugs and improving overall stability,
• fault-tolerant: issues or failures in one micro frontend are less likely to affect the entire application, as each module is isolated from the others.

Now that we know what micro frontends are, let’s take a look at the advantages this architectural approach may bring.

What are the advantages of a micro-frontend app?

The micro frontend architecture breaks down the monolithic architecture into smaller parts that can be managed independently, and that brings owners a number of advantages:

Independence

In a micro-frontend framework, teams can independently work on development and deployment of specific modules, making autonomous decisions throughout the process. This means that changes to one module do not require redeploying the entire application. In addition, different teams can work with their preferred technologies, frameworks, and languages, making it easier to adopt new technologies and experiment with different approaches (it’s best not to take this too far, however, as an abundance of different technologies may also complicate and slow down your app).

Scalability

I’ve already mentioned that modularity is at the core of micro-frontend architecture and this characteristic greatly promotes scalability. Developers can work on different modules simultaneously, so you can easily expand your application and add new functionalities as needed. You must have a proper architecture design, though, for that to work.

Resilience

Isolation between modules, which is the foundation of micro frontend architecture, ensures that a problem in one module does not spill over to others. Encapsulation of modules means that when a specific module fails or experiences issues, it is less likely to impact the entire application. In addition, it also simplifies troubleshooting and debugging, as developers can focus on the affected module rather than searching through the entire codebase.

Faster time-to-market

Indeed: micro-frontends can be deployed to production independently, so this type of architecture can dramatically increase productivity of your development team and shorten your time-to-market (TTM). There is just one important caveat, however: you can unlock this benefit only if your application is maintained by multiple teams (more on this further below).

Easier maintenance and upgrades

With micro-frontend architecture, developers can release updates incrementally – CTOs of large and complex applications will find that extremely valuable. By pushing updates module by module, instead of all at once, developers can monitor the impact of changes more effectively and respond quickly to any issues that arise.

Greater efficiency

Although micro frontend architecture organizes your development team into sub teams that work independently on the different modules, it also promotes greater collaboration among them. The teams need to define clear interfaces between individual modules, while working independently on delivery, which results in greater productivity.

What are the cons of micro frontend architecture?

While micro frontends can certainly work to your benefit in multiple cases, it’s important to remember that this architectural approach (like every other) has its drawbacks too. Consider the following:

Consistency challenges

Ensuring a consistent user experience across multiple micro frontends can be challenging. Since these micro frontends might be developed by separate teams using different technologies, there is a risk of incompatibilities in design, behavior, and the technology itself. Such a fragmented user experience won’t let you create a seamless and cohesive application.

One way to mitigate this challenge is to build a design system. It offers a set of standardized, reusable design elements, components, and guidelines that ensure a consistent experience. If you’d like to know more about this topic, I’d like to direct you to another article I’ve recently written about building design systems.

Shared dependencies

The shared dependencies among the different micro frontends may be difficult to handle. You’ll have to manage common libraries, components and any other resources. On top of that, you’ll also have to decide on the versioning and compatibility of these shared dependencies so that the whole application works smoothly and doesn’t create conflicts.

Otherwise, you may end up with numerous runtime errors and inconsistencies.

Increased complexity

Since micro frontend architecture is inherently modular, it can in fact complicate the development and maintenance. It involves orchestrating multiple frontends, managing communication between them, and coordinating deployment and operations – all of which require careful planning and well-defined processes.

Connecting all of those micro frontends requires a solid architectural plan. Without it, you can create a web of dependencies and communication channels tangled like spaghetti pomodoro.

Performance overhead

Micro frontend architecture can introduce performance overhead due to the increased number of network requests needed to load separate micro frontends. Each frontend module may require additional resources to load, which may also  prolong the initial load times in your system.

Moreover, the more versions of shared libraries you have, the more your app size will grow. This can negatively impact page load times and user experience. You should thus carefully plan a resource optimization strategy (Lazy loading? Code splitting?) to mitigate this risk.

Micro frontend testing

In a micro-frontend environment, testing becomes more complex due to increased interdependencies between components. End-to-end testing, in particular, might require coordination across multiple teams.

This can be remediated by automating the testing processes, using testing tools that support micro frontend architecture, and establishing clear guidelines for testing and quality assurance. Additionally, focusing on unit testing within individual micro frontends can help catch issues early in the development process.

Micro frontend versioning

Just like with testing, managing versions of each micro frontend and ensuring they work together seamlessly can be challenging. Since each micro frontend is developed and deployed independently, ensuring compatibility between different versions is crucial. Incompatibilities could arise due to changes in APIs, communication protocols, or shared dependencies. They obviously lead to inefficiencies, bottlenecks, and the development process will eventually go out of control.

To minimize the risk of this scenario, you should work on versioning strategies (CI/CD pipelines), as well as proper versioning documentation. And, keep your team informed about version updates and their potential impacts.

Demanding team communication

While micro frontend architecture enables individual teams to work more independently, they must be able to communicate and coordinate between each other to ensure alignment and compatibility between their respective micro frontends.

Is there a systematic way to mitigate this issue? Encouraging a culture of open communication and knowledge sharing can be an important component of ensuring your micro-frontend projects are delivered successfully and without friction.

Slower time-to-market in case of a small team

While the micro frontend architecture offers advantages for building medium and large-scale applications, if you have a more concise team, it may work to your disadvantage. Smaller team will have a lot more tasks at hand: they would have to work across several business domains and do so independently, which will actually slow down the work of a smaller team.

When to opt for micro frontend architecture

Micro frontend architecture has its advantages and disadvantages, which means you have a balancing task when it comes to this type of architecture. Below, I outline the scenarios when micro frontends will give you the benefits you may be looking for.

When building enterprise applications

Micro-frontend architecture best serves large applications – either those fast-growing and/or the complex ones. If you have many teams working on your frontend project, switching to micro-frontends will give you implementation independence. Such architecture is good at preventing blockages and bottlenecks.

When you require independent deployments

Micro frontends work very well when independent deployments are the priority. If you plan to update your tool often, but independently (without disrupting the entire application), micro frontends are your best option.

Thanks to modularity, you can easily modify, test and deploy different components without interfering with the functionality of other parts of the application. Fast-paced environments that also require agility are best served with this type of architecture. Opt for micro frontends when you want to be able to respond to changing marketing demands quickly.

When you work with different technology stacks

When your application is being developed by multiple teams that use different technology stacks, micro frontend architecture can accommodate those needs perfectly. Each team working on an independent module can select the technology stack that best suits its needs: different frameworks, programming languages, and libraries. Micro frontend architecture will allow different parts of the application to coexist harmoniously, even if they rely on entirely different technologies.

When you want to minimize the risk of failure

That’s exactly right! Micro frontend architecture is a great foundation for building modern apps because it helps to minimize the risk of failure (and we know that this is the top factor for losing customers). Micro frontend architecture allows to detach or detangle the different components of your application, so that when something fails, the rest of the application will continue to work.

When working with multiple, independent teams

Modern software applications are rarely the product of a single development team. Complex projects often require collaboration among various teams, each contributing expertise to different components. Micro frontend architecture aligns perfectly with such collaboration scenarios: it excels at enabling the collaboration between multiple, independent teams on a single application.

When you want to create a flexible application

If you want to create a product that can be configured differently for different types of users, micro-frontend architecture is a good choice. Take the Uber app, for instance: it is a single micro-frontend system with two unique application versions for drivers and passengers. Each version is equipped with distinct functionalities required for these user groups.

This type of architecture allows you to build one product that can be configured in a number of different ways, which also helps to maintain consistency of design.

When you want to modernize your existing solution gradually

Micro-frontends were actually created to allow for an easy migration and integration of legacy systems. Their purpose was to enable replacing the old components with micro-frontends gradually, so that businesses could modernize their application without a complete overhaul. As such, this architecture is perfect for modernizing existing legacy solutions.

When not to opt for micro frontends

As I mentioned, establishing a micro-frontend architecture can accommodate your needs and eliminate potential issues, as long as you carefully weigh in all the pros and cons. Take a look at the risks you must take into account in the following scenarios.

When you can’t find an experienced software engineering partner

Indeed: micro frontend framework is quite complex, so building scalable solutions in this model requires knowledge and experience. If someone doesn’t fully understand how to apply it, the consequences can be grave. The application must be independently responsive and that’s not always easy to achieve. If you decide to opt for this type of architecture, make sure you work with an implementation partner that has substantial experience with this type of architecture.

A badly-built app can result in highly-intertwined components. When various parts are tightly connected, separating them when you want to introduce new components may be very tricky, ultimately complicating the development process and slowing down growth.

How to migrate your existing application to micro frontend architecture?

The migration process involves decomposing the monolithic frontend into a set of independent, functionally cohesive modules that can be developed, deployed, and scaled independently. The goal is to create a more modular, scalable, and maintainable application. Here's a step-by-step guide to help you through the process:

Step 1: Understand the existing application

Before you begin the migration process, you have to prepare for it by thoroughly analyzing the existing architecture, identifying dependencies as well as data flows. Look at the technology stack behind it and evaluate its performance characteristics. This assessment is required to understand the potential challenges of the migration process and devising strategies that will address them effectively.

Step 2: Define domain boundaries

I mentioned earlier that typically, each micro frontend is responsible for a specific business function of your app. At this stage, you’ll need to divide your application into distinct business domains, so that when micro frontends are applied, each should encapsulate a specific piece of functionality, allowing them to operate independently.

This is how the micro frontend architecture extends the microservices concept on the backend. Isolating the components and allocating them to specific business domains and preventing cross-domain interference helps you to maintain a clear alignment between architecture and business objectives.

Step 3: Plan your technology stack

Choosing the right technology stack is obviously vital to the success of your micro frontend architecture. Decide on the technologies you want to use and remember that you can choose different tech stacks for every micro frontend, you also have to maintain consistency and the ability to manage complexities.

Developing a shared component library that houses common UI components can help you ensure the necessary consistency while minimizing duplication as well as version conflicts.

Step 4: Design the interaction model

Another key step towards successful migration to micro frontend architecture involves designing an effective interaction model – one that will ensure seamless communication with each other and the backend of your app. You should certainly take a prudent approach here: minimize direct dependencies between micro frontends and preserve their autonomy by avoiding coupling.

We have developed a dedicated open-source tool specifically to enable effective communication between micro frontends written in React and React Native: Eventrix. The tool not only enables seamless communication between micro frontends through events, but also allows to manage their state, so it’s helpful at maintaining both the flexibility and scalability required with this type of architecture.

Step 5: Prepare the infrastructure

Before delving into implementation, you also have to establish a foundation for your micro frontend architecture. This will be the core code base upon which all the individual micro frontends will be built.

The key here is to encapsulate functionalities. Encapsulation is an important and effective mechanism for preventing a domino-effect of component failure. This approach helps to ensure that, in case a part of an application fails, it is the only part that fails.

Step 6: Implement the micro frontends incrementally

The best approach when transitioning from monolith to micro frontend architecture is to do so incrementally. Start with the smallest, least critical parts of your application – this will allow you to see how the application behaves as you adjust to the new architecture as well as to easily solve any problems that arise (much easier than if you had started with the critical components). Likely, this will help you to refine your process, anticipate potential challenges, and fine-tune your strategies before tackling more complex micro frontends.

Step 7: Test thoroughly

This step is paramount to ensuring the reliability and compatibility of your micro frontends. As your teams work on their micro frontends, subject each and every one of them to rigorous testing. Use:

• functional tests to verify individual component behavior,
• integration tests to assess interactions between micro frontends, and
• end-to-end tests to validate the entire system's functionality.

Look specifically for those cases, where missing data on one micro frontend impacts the functioning of another. The goal is to identify hidden dependencies or performance bottlenecks that might impact the user experience, so that you can subsequently eliminate them.

Step 8: Deploy and monitor

Deploying micro frontends requires utmost attention to performance, security, and reliability. Once a micro frontend passes testing, deploy it to your production environment and closely monitor its performance. You must be able to detect anomalies and issues proactively (or as soon as they occur) to ensure a smooth user experience. You may in fact need to roll back deployments in case of serious issues.

Implementing relevant CI/CD pipelines and versioning strategies can help you automate this process. It’s critical to ensure a proper implementation – one that offers integrity with other micro frontends and meets accepted standards. Such a process can be quite extensive and complicated with micro frontend architecture.

Step 9: Update documentation and processes

This is a standard practice in any software development project: maintaining a documentation that thoroughly describes all the process and ensuring it’s up to date at all times. This is crucial, especially as your architecture evolves – as well as keeping your teams informed about any changes that may occur. A meticulous documentation will help to ensure a smooth transition to the new micro frontend environment as you roll out subsequent deployments.

The above steps should help you navigate the migration process from a monolithic application to micro frontend-based successfully.

Migrating to micro frontend architecture with RST Software

The most important thing to remember about shifting your existing app to micro frontend architecture is that the process in fact complex. Successful implementation requires a specific mindset; an approach that will ensure the components are as disentangled as possible. Working with a partner that has experience in implementing this kind of architecture can bring you closer to success.

If you’d like to know more about our approach and strategies, we’ll be more than happy to help. Just drop us a line via this quick contact form and we’ll get back to you to schedule a quick and free consultation.