Whether it’s online banking, social networks, or e-commerce platforms, APIs are the invisible backbone that keeps data flowing between distributed systems. Without them, there would be no seamless connections between apps, no online payments, and no personalised streaming recommendations.
But not all APIs are built the same. Some prioritise speed, others security, while some focus on flexibility. The architecture of an API determines how efficient, secure, and scalable it is.
In this article, you’ll learn what API architecture is, what components make it work, the types of API architecture you can choose from, and which protocols and formats enable smooth communication between systems.
What Is API Architecture?
API architecture is the blueprint for designing an API. It describes the structure, rules, protocols, and methods that define how an application programming interface (API) is built and operates.
It sets the standards for how different software systems communicate, what data they exchange, and how they do it.
Choosing the right API architecture style depends on your needs: secure bank transfers, real-time streaming, or interactive chat apps all demand different design patterns. A solid API architecture provides a clear system design blueprint for efficient, secure, and scalable interactions.
The 9 Components of API Architecture.
A robust API architecture is made up of many working parts. Here are the essentials every developer should understand:
1.Client and Server.
A client is a device or software that sends a request to a server to use data or services. The server processes the request and sends back a response.
- Examples: Typical clients include web browsers requesting web pages from a web server, or email applications retrieving emails from a mail server.
2. Endpoints.
API endpoints are specific paths or URLs that act as access points for certain functions. A client sends API requests to an endpoint to retrieve specific data, functions, or resources.
- Examples: A weather API might offer the URL https://www.wettertest.de/wetter?stadt=muenchen to get the current weather in Munich. For forecasts, it provides the endpoint https://www.wettertest.de/vorhersage?stadt=muenchen.
3. HTTP Methods.
APIs use various HTTP methods like GET, POST, PUT, and DELETE to specify different operations. For example, GET retrieves data, while POST is used to create new records.
- Example: A webmail service might send a request like GET https://www.emailtest.de/emails?inbox=true to retrieve a list of emails from the mail server.
4. Data Formats.
Interfaces define specific formats for requests and responses. Common formats include JSON (JavaScript Object Notation) and XML (Extensible Markup Language), which help structure data and make it easy to exchange between client and server.
5. Parameters.
Parameters are additional pieces of information passed in an API call. They let you specify or filter the request – for example, returning data for a specific time period or user.
- Example: The weather API URL https://www.wettertest.de/wetter?stadt=muenchen includes the parameter stadt=muenchen, specifying which city’s weather data to return.
6. Headers.
The header of an API request carries extra information such as authentication details, content type, or other metadata. This information is crucial for the security and efficiency of API communication.
7. HTTP-Status codes.
API architectures use HTTP status codes to communicate the result of a request. These codes are familiar from everyday web browsing.
- Examples: Status code 200 indicates success, while 404 means the requested endpoint was not found. Users don’t usually see a 200 code – it just means the page loads as expected. In contrast, a 404 typically shows a dedicated “Page Not Found” landing page informing the user the page doesn’t exist.
8. Protocols.
Protocols used in an API architecture define the rules and standards for communication.
- Examples: The most common standard for web APIs is REST (Representational State Transfer) because of its simplicity and flexibility. SOAP (Simple Object Access Protocol) is more complex but offers greater security.
9. Authentication and Security.
APIs need protection to prevent unauthorised access to sensitive data. This can be done with API keys or authentication tokens like OAuth (Open Authorisation).
- Example: When you sign in to a new app with your Google account, the app uses OAuth to securely access your account without knowing your password. Instead, it receives a token that manages access permissions.
What Types of API Architectures Are There?
There’s no single “best” API architecture. The right choice depends on your use case and goals. Here are three common types of API architecture:
Monolithic API Architecture.
Just like a monolith is a single, massive block of stone, a monolithic API architecture means that all API functions and components are bundled into one large application. The API communicates directly with a single database.
For smaller systems that don’t require frequent changes, this architecture is attractive because it’s easy to implement and manage. However, it has clear downsides: it’s hard to scale, and changes to any single component affect the entire API. If one part fails or has a bug, it can bring down the whole system.
Example of a monolithic API architecture in practice:
A retail company runs a small e-commerce shop where one API handles everything: loading the storefront, managing user data and account creation, processing orders, updating inventory, sending confirmation emails, and handling payments.
Microservices API Architecture.
In contrast to the monolithic model, a microservices architecture breaks the API into many small, independent services – microservices. Each microservice can, if needed, access its own database.
The big advantage is that services can be optimised, maintained, or replaced independently without affecting the rest of the system. This dynamic, modular design makes it highly scalable and flexible. The trade-off, however, is greater complexity and higher costs for development and management.
Example of a microservices API architecture in practice:
A streaming platform provider uses an API built from many specialised microservices: one handles the movie and series catalogue with detailed information on available titles; another manages the recommendation system with personalised suggestions; others handle video streaming, payment processing, user comments, and ratings. This design not only ensures smooth performance for millions of simultaneous users but also delivers high fault tolerance.
Serverless API Architecture.
As the name suggests, serverless architecture doesn’t rely on fixed, hardware-based server infrastructure. All API functions run in the cloud and only execute when needed. The cloud provider ensures the infrastructure is always available and delivers reliable performance. Billing is based on actual usage, with costs incurred for each API request.
For serverless API architecture, the specific use case is crucial. On the plus side, running APIs in the cloud saves time and money on on-premises server management and offers high availability – even for millions of users. However, this approach makes you highly dependent on your cloud provider and limits customisation options.
JSON und XML: The Languages of APIs.
JSON and XML are critical data formats in API architecture.
JSON (JavaScript Object Notation).
JSON is easy to read for both humans and machines. It consists of key-value pairs, where the key acts like a label or category and defines what value is provided.
JSON is also platform-independent and compatible with many programming languages. Its flexibility makes it ideal for web applications and services that need fast, efficient data exchange.
- Example: In the following JSON code, “name” is the key and “Tom” is the value:
{
„name“: „Tom“,
„animal“: „Dog“
“character”: [“friendly”, “playful“]
}
XML (Extensible Markup Language).
XML provides a strictly hierarchical structure for data using nested tags. These tags function similarly to keys in JSON, defining which values are included.
Many people first encounter XML in the context of websites, as web pages often rely on XML for their underlying structure.
Like JSON, XML is both platform- and language-independent. It also allows you to define your own tags and structures, offering a high degree of flexibility to meet different requirements.
- Example:
<animal>
<name>Tom</name>
<art>Dog</art>
<character>
<trait>friendly</trait>
<trait>playful</trait>
</character>
</animal>
While JSON is preferred for its efficiency and simplicity – especially in web-based applications – XML is often used in more complex or regulated environments because of its precise structure and extensibility. The choice between JSON and XML depends heavily on the specific requirements of the project and the development team’s preferred workflows.
An Overview of the 5 Most Important Standards and Protocols for API Architectures.
Every API architecture has its own advantages that make it suitable for different use cases and applications. However, architecture shouldn’t be confused with the protocol used: API architecture defines the conceptual framework and principles for how APIs are designed and used, while protocols specify the rules and standards for API communication.
REST APIs: Simple and Flexible.
REST (Representational State Transfer) is a standard for designing network-based applications such as web applications or mobile apps. It establishes a framework for communication between client and server.
Each endpoint can be accessed via a unique URL. For example, if a customer wants to book a hotel room, they can view a list of available rooms using a URL like: https://www.testhotel.com/room.
A REST API uses standardised HTTP methods like GET, POST, PUT, and DELETE to perform operations such as reading, creating, updating, or deleting specific resources. For instance, if a customer has already booked a room but wants to change the travel dates, this is handled with a PUT API call.
In REST architecture, every interaction is stateless, meaning each API request is independent and the server doesn’t store session data. This requires each request to include all the information the server needs to understand and process it. While this can mean sending more data with each call, it greatly improves reliability and performance overall.
SOAP APIs: Secure and Reliable.
SOAP stands for Simple Object Access Protocol and is a protocol standard used for exchanging message data between network applications. It relies on XML to structure messages and typically uses HTTP or SMTP (Simple Mail Transfer Protocol) for transmitting them.
A key feature of SOAP is its strict specification and structured format, which makes it highly reliable.
Because SOAP supports web service specifications like WS-Security for encryption and authentication, it’s often used for applications and services that require a high level of security, such as bank transactions.
SOAP is generally seen as more cumbersome than REST, especially for simple use cases. This is due to its complex message structure and the overhead created by the XML format. However, SOAP remains a popular choice for enterprise-level applications where data security and reliability justify the added complexity.
GraphQL: A Modern REST Alternative.
GraphQL is a query language for APIs developed by Facebook, designed as a modern alternative to traditional REST and SOAP APIs. It enables highly optimised, client-driven data queries – ideal for user profiles and feeds on social media platforms.
This technology allows the client to specify exactly what data it needs, avoiding overfetching (retrieving too much irrelevant data) and underfetching (retrieving too little or incomplete data).
Additionally, GraphQL only requires a single endpoint – all queries go through a central /graphql route instead of separate URLs for each resource.
Another key advantage is GraphQL’s ability to merge multiple queries into a single request (known as batch requests), reducing the number of network calls. This is particularly useful in high-latency or low-bandwidth environments, such as mobile networks.
RPC and gRPC: Remote and Asynchronous.
RPC stands for Remote Procedure Call. It’s a communication protocol that allows functions or processes to be executed on a physically remote system as if they were local. This reduces complexity for developers and simplifies building and deploying functions.
RPC supports both synchronous and asynchronous communication. Clients can wait for a response (synchronous) or continue with other tasks until the response arrives (asynchronous).
This approach is widely used in distributed systems and in developing network applications like web services or cloud-based services, where simplifying direct network communication is critical.
Instead of traditional RPC, many developers use gRPC, an extended framework by Google known for its high performance and low latency. It’s particularly well-suited for microservices and applications that require high scalability.
Google’s technology leverages the faster, more secure HTTP/2 transport protocol and uses the efficient Protobuf (Protocol Buffers) serialisation format. It supports various API interaction models, including Unary (simple request-response), Server Streaming, Client Streaming, and Bidirectional Streaming.
While gRPC is specifically designed for modern, decoupled systems and microservice architectures, traditional RPC systems are somewhat more flexible and suitable for a broader range of use cases.
OData: Open and Standardised
OData (Open Data Protocol) is an open technology based on REST that was designed to create and use standardised, interoperable REST APIs.
It enables easy publishing, editing, and retrieval of data over the internet. OData aims to make accessing data sets as straightforward as the web makes accessing documents, using familiar web technologies like HTTP, Atom Publishing Protocol (AtomPub), and JSON.
OData can handle complex data queries via URLs, supporting operations such as filtering, sorting, pagination, and managing associations between data sets. Developers can use OData to build RESTful services that let clients interact flexibly with data.
By standardising access to different types of data sources (like relational databases, file systems, content management systems, and traditional web services), OData simplifies the development of platform- and device-independent applications. This makes it a valuable tool for developers creating data-driven applications that need to integrate with diverse data sources with minimal effort.
Mastering API Architecture Is Easy with Lobster.
When it comes to software development and digital transformation, having a clear API architecture is just as important as having an overall API strategy.
A strong API architecture ensures efficient integration of systems, secure API gateway management, and scalable data flows.
When you design an API architecture, choosing the right protocol, data format, and API architecture style matters. Lobster’s comprehensive integration solutions and no-code tools make developing the API you need easy – even if you’re not a developer.
Our central data platform supports all major industry standards, offering seamless integration with external partners and systems. With robust API management and a wide range of prebuilt connectors, the Lobster platform ensures secure, efficient API interaction without the headaches.
Ready to simplify your API landscape?
Contact us to learn how Lobster can help you build the right API architecture for your business – no coding required.
