Microservices vs. APIs: Relationship and Differences Between Them

Godwin Alexander Ekainu
Godwin Alexander Ekainu
December 31, 2023 · 21 min read
Microservices vs. API: Relationship and Difference Between Them

Microservices are a type of software architecture that allows developers to build applications as a collection of small, independent services. This approach contrasts with the traditional “monolithic” architecture, in which an application is built as a single, large unit.

Microservices have become increasingly popular in recent years due to their many advantages. For example, microservices can be easier to develop and deploy than monolithic applications. They also tend to be more scalable and more resilient to failures.

On the other hand, APIs (Application Programming Interfaces) provide a way for different software applications to communicate with each other.

An API allows one application to “expose” its functionality to another application, which can then “consume” that functionality. For example, when you use a mobile app to book a hotel room, the app is likely using an API to communicate with the hotel’s reservation system.

In general, microservices and APIs are two very different things. However, they are often used together.

To understand the relationship between microservices and APIs, it's first important to understand the different functions that each one serves. An API is a set of rules and protocols that allows software applications to interact with each other. In contrast, a microservice is a self-contained unit of functionality that can be independently deployed and operated. While an API defines how software components should interact, a microservice provides a concrete implementation of those interactions.

While they serve different purposes, microservices and APIs are often used together to build complex applications. For example, a microservice may expose an API that allows other services to trigger its functionality. Alternatively, an API might be used to aggregate data from multiple microservices. In either case, the combination of microservices and APIs can be used to build sophisticated applications that are more resilient and scalable than traditional monolithic architectures.

In this post, we'll explore the relationship between microservices and APIs and highlight their key differences. We'll also discuss when it's appropriate to use each one.

What Is an API (Application Programming Interface)?

An API is a set of programming instructions that allows the software to interact with other software. In other words, it is a way for different applications to communicate with each other.

APIs are typically used to access data or functionality that is or isn’t readily available through the user interface. For example, the Google Maps API allows developers to create applications that can display map data and directions. The Twitter API allows developers to create applications that can send and receive tweets. By using an API, developers can save time and effort by reusing existing code rather than having to write their own from scratch.

Alternatively, an API could allow a mobile app to control a piece of hardware, such as a drone or a robotic arm. By providing access to hidden data and functionality, APIs can open up new opportunities for both developers and users alike.

An API generally consists of a number of functions or subroutines that can be called by a program. Each function corresponds to a particular task that needs to be performed.

Here are five basic request methods that can be made with HTTP APIs:

  • GET: collect information

  • PUT: edit and add to already existing data in a collection

  • POST: add data to a collection

  • PATCH: update data in a collection

  • DELETE: delete data from a collection

The API also includes a number of data types that can be used by the functions. For example, the Google Maps API includes functions for displaying maps and for retrieving directions. It also includes data types for representing geographical coordinates and street addresses.

By using the functions and data types in the API, developers can create applications that make use of the functionality provided by the API without having to understand the underlying implementation details.

Types of APIs

APIs can be divided into several categories based on their purpose and how they are implemented.

The most common classification can be based on their public availability:

  • public APIs

  • private APIs

  • partner APIs

Public APIs

A public API is an interface that allows third-party developers to access and use a company’s data and functionality. Public APIs are typically used to expose data and functionality to external partners or to allow third-party developers to build new products and services that complement a company’s existing offerings. For example, Amazon’s eCommerce platform has a public API that allows developers to build shopping apps that access Amazon’s product catalog and checkout process.

Public APIs can be an important part of a company’s business strategy. By opening up data and functionality to third-party developers, companies can tap into new markets and create new revenue streams. In addition, public APIs can help build brand awareness and drive traffic to a company’s website or app. For example, Twitter’s public API has been used by thousands of developers to build new Twitter apps and services. As a result, Twitter has been able to grow its user base and become one of the most popular social networking platforms in the world.

Public APIs can also help companies improve their products and services. By giving third-party developers access to a company’s data and functionality, companies can get feedback and suggestions for how to improve their offerings. In addition, public APIs can be used to gather data about how users interact with a company’s products and services. This data can be used to improve the user experience and make better product decisions.

Overall, public APIs can be a powerful tool for companies looking to grow their business or improve their products and services. By opening up data and functionality to third-party developers, companies can tap into new markets, create new revenue streams, and gather valuable feedback about their products and services.

Private APIs

A private API is an interface that is not publicly accessible. Private APIs are often used by developers to access internal data or functionality that is not exposed to the outside world.

One of the most common uses for private APIs is accessing internal data stores. This data may include sensitive information such as customer records or financial information. By using a private API, developers can ensure that this data is only accessible to authorized users.

Another common use for private APIs is connecting to internal databases or other services. This can be very helpful for developers who need to access data that is not publicly available.

Private APIs can be very useful in certain situations, but they can also pose a security risk if they are not properly secured. Developers should only use private APIs when absolutely necessary and should always ensure that the API is properly secured before using it.

Partner APIs

Partner APIs, also known as external APIs, allow a business to integrate features and functionalities from external sources into their own platform. This allows for a more comprehensive user experience and can also save time and resources for the company.

For example, a retail website may use a partner API to incorporate real-time shipping rates and tracking information from a shipping company. Or, a social media app might utilize a partner API to add geolocation tagging capabilities for photos shared on the platform.

Partner APIs can also open up new revenue streams for businesses by allowing them to access high-demand data or services from other companies. For instance, a travel booking website may use an airline's API to provide flight booking options to their customers.

Overall, partner APIs play a crucial role in today's technology-driven marketplace by facilitating seamless integrations and enhancing the capabilities of a platform.

API Protocols

API protocols govern the way that applications communicate with each other. These protocols determine how information is formatted, transmitted, and received between two systems.

Some common API protocols include REST (Representational State Transfer), GraphQL, and SOAP (Simple Object Access Protocol).

Each protocol has its own set of advantages and disadvantages, making it important for developers to carefully consider which protocol best suits their needs before building an API. For example, REST is popular due to its simplicity and flexibility, while SOAP offers more security features for sensitive data transmission.

Ultimately, the use of proper API protocols ensures smooth and efficient communication between applications.


The REST (Representational State Transfer) API is a standardized architecture for creating web services. It uses HTTP requests to GET, PUT, POST, and DELETE data.

REST is not a specific technology but rather a set of constraints and principles that ensure scalable and efficient communication between systems. By adhering to these constraints, REST APIs have increased flexibility and maintainability.

One of the key principles of REST is the separation of client and server responsibilities. The client sends an HTTP request to the server, which then processes the request and sends back an HTTP response containing the requested information or actions taken on the resource. This allows for decoupling between the client and server, allowing for easier implementation and modification of either component in the future.

Another important principle is the use of a uniform interface, where the structure and organization of resources are clearly defined. This allows for easy interaction between different systems using the same REST API.

Overall, REST API provides a standardized and efficient means of communication between systems, allowing for greater flexibility and scalability in web development.


GraphQL is a query language for API development that was first developed and used internally by Facebook in 2012. It allows clients to request specific data from a server, giving more flexibility and efficiency compared to traditional REST APIs.

Instead of multiple endpoint URLs for different types of data, GraphQL uses a single endpoint and allows the client to specify exactly what data they want to retrieve. This eliminates over-fetching or under-fetching of information, as the client only receives the exact data requested.

Along with fetching data, GraphQL also allows for modifications to be made through mutations. These function similarly to POST, PATCH, and DELETE requests in REST APIs.

GraphQL can also be used for real-time updates through subscriptions. This allows clients to receive updates instantly when a change is made on the server side, rather than continuously polling for updates.

Overall, GraphQL offers a more efficient and flexible way for clients to interact with APIs. It has gained popularity in recent years and is now used by major companies such as Twitter, Shopify, and GitHub.

SOAP (Simple Object Access Protocol)

The SOAP protocol, also known as the Simple Object Access Protocol, is a messaging protocol used for exchanging information in a decentralized and distributed environment. It relies on XML as its message format and usually relies on other application layer protocols, such as HTTP or SMTP, for message negotiation and transmission.

SOAP allows for communication between different applications running on different platforms using different programming languages. This is achieved through the use of XML to define the structure of the message being sent.

SOAP messages are typically sent as HTTP requests, with the SOAP message being included in the body of the request. The SOAP message must adhere to a specific structure which includes a header and a body. The header contains meta information, such as authentication and payment details, while the body contains the actual message being sent.

SOAP also has a binding framework, which defines how SOAP messages should be processed. One commonly used binding is the SOAP over HTTP binding, where SOAP messages are encapsulated in HTTP requests and responses.

Overall, SOAP allows for communication between applications using a standardized messaging format, making it a useful tool for distributed environments.

What Are APIs Used For?

APIs, or Application Programming Interfaces, are used to allow different software systems to communicate and exchange data with each other. They act as a bridge between different applications, allowing them to access and use certain functionality or data from another application.

For example, an e-commerce website may use an API to connect to a payment processing system in order to process customer payments. Another common use of APIs is for social media platforms to allow third-party developers access to their platform’s features, such as the ability to automatically post content or pull user profile information.

APIs also play a significant role in the development process by providing a set of defined specifications and protocols for how one application can interact with another. This allows for easier and more efficient development, as well as the ability for different software systems to integrate with each other.

Overall, APIs are an essential component in modern software development and enable seamless communication and integration between various applications.

What Are the Benefits of Using APIs?

Some specific benefits of using APIs include increased efficiency and automation, as well as enhanced security measures. By streamlining communication between different systems, repetitive tasks can be automated and completed with minimal human interaction. Additionally, API usage allows for tighter security measures by restricting access to certain data and actions within the system.

The use of APIs also opens up opportunities for innovation and customization. Companies are able to quickly integrate new features and capabilities into their existing software systems without extensive development and testing. This allows for a more dynamic and responsive business model, as well as potential revenue growth through partnerships and external integrations.

Overall, the use of APIs can greatly benefit companies by improving efficiency, security, and innovation opportunities within their software systems.

Ease of Integration

One of the benefits of using APIs is the ease of integration.

By using an API, you can easily integrate new features into your existing workflow without having to start from scratch.

In many cases, you can simply make a few calls to an API and then start using the new feature right away. This can save you a lot of time and effort when compared to writing new code or integrating with a new system.

Additionally, APIs can allow you to take advantage of preexisting code or data that you may not have access to otherwise. By using an API, you can tap into a wealth of information or functionality that you wouldn’t be able to use otherwise. This can be a great way to save time and effort when developing new features or functionality for your software.


When building an application, you want to be able to scale quickly and easily to meet the demands of your users.

Adding new features should not be a time-consuming and difficult process.

One way to achieve this is by using APIs (Application Programming Interfaces). APIs allow you to abstract away the underlying implementation, making it easy to add new functionality without having to make changes to the code that has already been written.

In addition, well-designed APIs can provide a consistent interface regardless of the programming language or platform that is being used. This makes it easy for developers to work with the API, regardless of their background.

As a result, using an API can help to make your application more scalable and easier to expand.


Another benefit of using APIs is that they can help to automate tasks.

For example, if you need to retrieve data from a remote server regularly, you can use an API to fetch the data and store it locally automatically. This can save you a lot of time and effort, as you don’t need to fetch the data each time manually.

Similarly, if you need to update a database or other system with new data regularly, you can use an API to push the data to the system automatically. This can again save you a lot of time and effort, as you don’t need to update the system each time manually.

In general, using an API can help to automate any task that would otherwise require manual intervention.

What Is A Microservice?

Microservices are a type of software architecture that allows developers to build applications as a collection of small, independent services. Each microservice is designed to perform a specific task, and they can be deployed and scaled independently of each other.

This approach has several benefits over traditional monolithic architecture, including increased flexibility, improved scalability, and reduced development and deployment times.

  • First, in a microservices architecture, each service is responsible for a single functionality, such as user authentication or product catalog management. These services can be developed and deployed independently of each other, making it easier to update and maintain the application as a whole. This architecture allows for greater flexibility in the development process, as different teams can work on different services simultaneously.

  • Second, it makes identifying and fixing issues easier, as each service can be tested and updated independently. In a microservices architecture, each service is responsible for a single functionality, such as user authentication or product catalog management. These services can be developed and deployed independently of each other, making it easier to update and maintain the application as a whole.

  • Finally, it enables applications to be more scalable, as individual services can be increased or decreased in response to changes in demand. For example, if the user authentication service is receiving more traffic than the product catalog service, it can be scaled up without affecting the rest of the application.

Microservices are not without their challenges, however. One of the biggest challenges is communication between services, as each service needs to be able to communicate with the others in order to function properly. Another challenge is managing dependencies, as each service is likely to have its own dependencies on other services.

Despite these challenges, microservices offer a number of benefits that make them an attractive option for many applications.

What Are Microservice Used For?

Microservices are a type of software architecture that allows for individual components of a larger application to be built, deployed, and managed independently. This approach contrasts with the more traditional monolithic approach, where an application is built as a single unit. Microservices can be beneficial because they allow for greater flexibility and scalability.

Microservices Are Used for Service Independence

Microservices are a software development technique that structures an application as a collection of small, independently deployable services. This approach is in contrast to traditional monolithic architectures, in which an application is built as a single, large unit.

There are several benefits of using microservices for service independence.

  • First, it enables each service to be developed and deployed independently of the others. This allows for more rapid development and deployment cycles, as well as more flexible scaling.

  • Second, microservices can be implemented in different programming languages, making finding the right technology stack for each service easier.

  • Finally, because each service is self-contained, it is easier to identify and isolate problems when they occur.

Microservices Are Used for More Effective Data Processing

One of the most important reasons for using microservices is that they allow for more effective data processing. When data is spread out across multiple services, it can be processed in parallel, which can lead to significant performance gains.

In addition, microservices can be scaled independently so that each service can be sized according to its needs.

Benefits of Using Microservices

Microservices are a type of software architecture that allows developers to build applications as a set of small, independent services. This approach has a number of advantages over more traditional monolithic architectures.

  • First, it allows for greater flexibility and efficiency in development, as each service can be developed and deployed independently.

  • Additionally, microservices can be more easily scaled up or down as needed without having to make changes to the entire application.

  • Finally, this approach can improve application stability and resilience, as any issues with one service can be isolated without affecting the rest of the application.

Overall, microservices offer a number of benefits that make them an attractive option for modern application development:

Greater Flexibility

Microservices offer a number of benefits over traditional monolithic architectures, including greater flexibility.

Each service can be deployed and scaled independently with microservices, allowing you to adapt to changing needs easily. This can be a major advantage when you need to make changes to your system, as you can deploy the new services without affecting the rest of the system.

In addition, microservices allow you to use different technologies for different services, further increasing your flexibility. For example, you could use one language for your web front end and another for your database backend.

Finally, microservices also make it easier to roll back changes if necessary, as you can simply un-deploy the affected service without affecting the rest of the system.


Efficiency is one of the key benefits of using microservices. When services are broken down into smaller, independent components, it becomes much easier to scale them up or down as needed. For example, let's say you have a monolithic application with dozens of different features. If one of those features becomes popular and starts getting a lot of traffic, the entire application will need to be scaled up to accommodate the increased demand. However, if you're using microservices, you can simply scale up the service that's being used most frequently without affecting the other services. This can save a lot of time and resources.

Another way that microservices can increase efficiency is by making it easier to roll out updates and new features. With a monolithic application, if you want to add a new feature or update an existing one, you have to deploy the entire application again. This can be a time-consuming and error-prone process. However, with microservices, you can deploy only the service that's been updated, which is usually much quicker and easier.

Finally, microservices can help improve your team's efficiency by allowing them to work on different parts of the system concurrently. With a monolithic application, if one team is working on a new feature, they have to wait for the other teams to finish their work before they can deploy the changes. However, with microservices, each team can work independently on their own service, and then those changes can be deployed separately. This means that your team can get new features and updates out to your users much faster.

Stability and Resilience

Another one of the biggest advantages of using microservices is that it increases the stability of an application. Since each microservice is self-contained, if one service goes down, the rest of the application can continue to function normally. This is in contrast to a monolithic architecture, where a single failure can bring down the entire application.

In addition, microservices are often easier to deploy than monolithic applications. When deploying a microservice-based application, only the changed services need to be redeployed, which can significantly reduce downtime.

Last but not least, another benefit of microservices is that they promote resilience. When an application is built using microservices, it can be more easily replicated across multiple servers. This provides increased availability in the event of a server failure. Additionally, microservices can be deployed in different regions, providing protection against outages that might occur in a single location.

The Bottom Line of Microservices and APIs: How They Work Together and How They Benefit Each Other?

When it comes to web development, there are two main approaches: monolithic and microservices. In a monolithic architecture, all components are tightly coupled and deployed together as a single unit. This approach is simple and straightforward but can be inflexible and difficult to scale. Conversely, microservices are small, independent components that can be deployed and scaled independently. This makes them much more flexible and scalable than monolithic architectures but also more complex.

One way to think of microservices is as a set of Legos: each one is its own independent piece that can be combined with other pieces to build something bigger. In the same way, each microservice can be deployed and scaled independently, making it easy to add or remove functionality as needed.

Of course, simply having a set of independent components is not enough - they also need to be able to communicate with each other. This is where APIs come in. An API (Application Programming Interface) is a set of rules that defines how two software components should interact. In the context of microservices, an API defines how a given microservice can be accessed by other microservices.

For example, let's say you have a microservice that stores data in a database. Another microservice might need to retrieve this data in order to display it on a web page. In order to communicate between these two services, you would need to define an API that specifies how the data should be structured and what methods should be used to access it. Once you have defined this API, any number of other microservices can use it to communicate with the data-storing service.

In summary, microservices are small, independent components that can be deployed and scaled independently. They communicate with each other via APIs, which define the rules for how data should be structured and accessed. This makes for a more flexible and scalable overall architecture.

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