AJAX - Using AJAX in Micro-Frontend Architectures

Introduction

Micro-frontend architecture is a modern web development approach where a large application is divided into smaller, independent frontend applications. Each micro-frontend is developed, tested, and deployed separately by different teams while working together to form a single user interface. AJAX plays a crucial role in this architecture by enabling each micro-frontend to communicate with backend services independently without requiring page reloads.

Unlike traditional monolithic applications where all frontend components depend on a single codebase, micro-frontends allow different modules such as user management, product catalog, shopping cart, notifications, and reports to function independently. AJAX enables these modules to retrieve and update data asynchronously, making the application faster and more scalable.

What is a Micro-Frontend?

A micro-frontend is a self-contained frontend module that represents a specific business feature. Each module has its own code, styles, APIs, and deployment process.

For example, an e-commerce website can be divided into:

  • Product Listing Module

  • Product Details Module

  • Shopping Cart Module

  • User Profile Module

  • Payment Module

  • Order History Module

Each module communicates with its own backend service using AJAX requests.

Role of AJAX in Micro-Frontends

AJAX allows every micro-frontend to fetch and update data independently.

Instead of loading the entire application whenever data changes, only the required module communicates with the server.

Example:

The shopping cart module sends an AJAX request to retrieve cart items.

GET /api/cart

The profile module sends another request.

GET /api/profile

Both requests happen simultaneously without affecting each other.

Why AJAX is Important in Micro-Frontend Architecture

AJAX provides several advantages.

Independent Data Loading

Each micro-frontend loads only the data it needs.

Example

The dashboard page contains four modules:

  • Weather

  • Notifications

  • Calendar

  • News Feed

Each module independently loads its data using AJAX.

This improves loading speed because users do not have to wait for every module before interacting with the page.

Independent Backend Services

Different teams may build different backend services.

Example

Product Service

/api/products

Cart Service

/api/cart

Payment Service

/api/payment

Each micro-frontend communicates with its own backend using AJAX.

This reduces dependency between teams.

Faster Deployment

Suppose the shopping cart team introduces a new feature.

Only the cart module needs to be updated.

Other modules continue working normally because their AJAX requests remain unchanged.

Better Fault Isolation

If one backend service becomes unavailable, only the corresponding micro-frontend is affected.

Example

The review service stops responding.

The review module displays

Unable to load reviews.

Meanwhile,

  • Product list continues working.

  • Shopping cart works normally.

  • Payment module remains functional.

This increases application reliability.

Communication Flow

A micro-frontend usually follows this workflow.

User Action

↓

Micro-Frontend

↓

AJAX Request

↓

Backend Service

↓

Database

↓

JSON Response

↓

Micro-Frontend Updates UI

Example

A user clicks "Load Orders."

The Order module sends

GET /api/orders

The server returns

[
    {
        "orderId":101,
        "amount":450
    },
    {
        "orderId":102,
        "amount":1200
    }
]

Only the order section updates.

Example Architecture

Main Application

│

├── Product Module

├── Cart Module

├── User Module

├── Review Module

└── Payment Module

Each module sends AJAX requests independently.

Product Module

↓

GET /products

Cart Module

↓

GET /cart

User Module

↓

GET /profile

Payment Module

↓

POST /payment

Each request is completely independent.

Using Fetch API in Micro-Frontends

Modern micro-frontends commonly use the Fetch API.

Example

fetch('/api/products')
.then(response => response.json())
.then(data => {
    console.log(data);
})
.catch(error => {
    console.log(error);
});

This request affects only the Product module.

Other modules continue functioning.

Loading Multiple Modules Simultaneously

Suppose the homepage contains three independent modules.

  • User Profile

  • Notifications

  • Messages

Each module sends an AJAX request.

Promise.all([
    fetch('/api/profile'),
    fetch('/api/messages'),
    fetch('/api/notifications')
])
.then(responses => Promise.all(
    responses.map(response => response.json())
))
.then(data => {
    console.log(data);
});

All requests execute simultaneously.

This reduces the overall loading time.

Error Handling

Each micro-frontend handles its own errors.

Example

fetch('/api/orders')
.then(response => {
    if(!response.ok)
        throw new Error("Request Failed");
    return response.json();
})
.then(data => {
    console.log(data);
})
.catch(error => {
    console.log(error.message);
});

If the Orders API fails, only the Orders module shows an error.

Other modules continue working.

Authentication

Most AJAX requests require authentication.

A common approach is using JSON Web Tokens (JWT).

The browser sends the token with every request.

fetch('/api/profile',{
headers:{
Authorization:"Bearer token_here"
}
});

The server verifies the token before returning data.

Sharing Data Between Micro-Frontends

Sometimes one module needs information from another.

For example,

The Cart module updates the cart count.

The Header module displays the updated cart icon.

Instead of making duplicate AJAX requests, applications often use shared state management, custom browser events, or a communication layer to notify other micro-frontends about changes. This reduces unnecessary network traffic and keeps all modules synchronized.

Avoiding Duplicate AJAX Requests

Different modules may request identical information.

Example

Header Module

GET /api/profile

Dashboard Module

GET /api/profile

Instead of sending two requests, the application can cache the first response and share it with other modules. This reduces server load and improves performance.

Cross-Origin Resource Sharing (CORS)

Micro-frontends may communicate with different servers.

Example

Products

https://products.example.com

Payments

https://payments.example.com

Since these are different origins, the servers must enable CORS by sending the appropriate HTTP headers. Without proper CORS configuration, browsers block cross-origin AJAX requests for security reasons.

API Gateway

Many micro-frontend systems use an API Gateway.

Instead of contacting multiple backend services directly, every AJAX request passes through a single gateway.

Browser

↓

API Gateway

↓

Product Service

↓

Cart Service

↓

Payment Service

Benefits include:

  • Centralized authentication

  • Rate limiting

  • Request routing

  • Logging

  • Security policies

  • Simplified client configuration

Performance Considerations

To achieve better performance:

  • Load only the modules visible to the user.

  • Cache frequently requested data.

  • Compress API responses using Gzip or Brotli.

  • Use pagination for large datasets.

  • Cancel obsolete AJAX requests when users quickly navigate between pages.

  • Avoid duplicate requests by sharing cached responses.

  • Use lazy loading so modules are loaded only when required.

Advantages of AJAX in Micro-Frontend Architecture

  • Allows independent development of frontend modules.

  • Enables separate deployment for each module.

  • Improves application scalability.

  • Reduces page reloads.

  • Supports faster data retrieval.

  • Makes applications more responsive.

  • Allows multiple teams to work simultaneously.

  • Improves fault isolation.

  • Enables independent backend services.

  • Enhances user experience through asynchronous communication.

Limitations

  • Managing communication between modules can become complex.

  • Authentication must be handled consistently across all micro-frontends.

  • Multiple AJAX requests may increase network traffic if not optimized.

  • Debugging interactions across independently deployed modules can be more difficult.

  • Version mismatches between frontend modules and backend APIs may cause compatibility issues.

  • Proper CORS configuration is essential when services are hosted on different domains.

Best Practices

  • Keep each micro-frontend focused on a single business function.

  • Design RESTful APIs with consistent request and response formats.

  • Implement robust error handling for every AJAX request.

  • Use caching to minimize repeated server calls.

  • Secure all requests using HTTPS and authentication tokens.

  • Monitor AJAX performance using browser developer tools and logging systems.

  • Avoid unnecessary communication between modules.

  • Use an API Gateway when multiple backend services are involved.

  • Document APIs clearly so different teams can integrate their micro-frontends reliably.

  • Test each micro-frontend independently before integrating it into the overall application.

Conclusion

AJAX is a foundational technology in micro-frontend architectures because it enables independent modules to communicate with backend services asynchronously. Each micro-frontend can load, update, and manage its own data without interrupting other parts of the application. This approach supports modular development, faster deployments, better scalability, improved fault isolation, and a smoother user experience. By combining AJAX with proper API design, authentication, caching, and performance optimization, developers can build large, maintainable web applications that remain efficient as they grow in size and complexity.