Various API Architectures You Should Know (Starting with Keploy.io!)
APIs (Application Programming Interfaces) are the backbone of modern software systems. Whether you're building a web app, mobile app, or a microservice, APIs are what connect everything. But not all APIs are the same — there are different architectural styles that developers use based on their needs, scale, and structure.
Before diving into those styles, let’s talk about Keploy.io, a platform that makes testing these APIs much easier — no matter what architecture you're using.
Keploy.io: Test APIs, No Matter How They're Built
Whether you're using REST, GraphQL, gRPC, or even SOAP (yikes), Keploy helps you capture real API traffic and generate test cases and mocks automatically. This saves developers hours of manual testing work and ensures more reliable deployments. It's especially powerful for microservices, where testing APIs independently becomes a headache.
Now, let’s explore the various API architectures out there, their pros, cons, and where they shine.
1. REST (Representational State Transfer)
REST is the most common API style you'll see today. It's simple, stateless, and uses standard HTTP methods like GET, POST, PUT, DELETE.
Pros:
- Simple and easy to understand.
- Widely supported by tools and frameworks.
- Scalable and stateless, good for microservices.
Cons:
- Over-fetching or under-fetching data is common.
- Versioning can get messy.
Use case: Ideal for CRUD-based applications, internal tools, and where simplicity is key.
- GraphQL
Developed by Facebook, GraphQL gives clients the power to ask for exactly the data they need — no more, no less.
Pros:
- No over-fetching or under-fetching.
- Great for mobile apps (reduces data usage).
- Strongly typed and introspectable.
Cons:
- Complex setup for beginners.
- Caching is harder compared to REST.
- Needs thoughtful schema design.
Use case: Great for client-heavy apps, mobile apps, and scenarios where bandwidth matters.
- gRPC (Google Remote Procedure Call)
gRPC is a high-performance, open-source universal RPC framework developed by Google. It uses Protocol Buffers instead of JSON, making it super fast and compact.
Pros:
- High performance, low latency.
- Strong typing via protobuf.
- Supports bidirectional streaming.
Cons:
- Harder to debug compared to REST.
- Not natively browser-friendly (needs proxy).
Use case: Ideal for internal service-to-service communication in microservices, real-time apps, and large-scale systems.
- WebSockets
WebSockets provide a full-duplex communication channel over a single, long-lived TCP connection. It’s not strictly an API style but is often used alongside REST or GraphQL.
Pros:
- Real-time, two-way communication.
- Lower latency than polling.
Cons:
- More complex to scale.
- Harder to cache or test without proper tools.
Use case: Chat apps, live dashboards, multiplayer games — anything real-time.
- SOAP (Simple Object Access Protocol)
SOAP is the granddaddy of APIs. It’s XML-based and highly structured, with built-in error handling and strict standards.
Pros:
- Very formal and standardized.
- Built-in security and reliability.
Cons:
- Verbose and heavy.
- Harder to work with compared to modern APIs.
Use case: Still used in enterprise, banking, and legacy systems.
- Serverless APIs (via API Gateways)
With the rise of serverless architectures, many APIs are now built using cloud functions (like AWS Lambda or GCP Cloud Functions) and exposed via API Gateways.
Pros:
- No server management needed.
- Pay-per-use pricing.
- Scales automatically.
Cons:
- Cold starts can affect performance.
- Vendor lock-in.
Use case: Lightweight APIs, prototypes, event-driven systems.
Final Thoughts: Which Architecture Should You Choose?
There’s no one-size-fits-all answer — it depends on your application, team size, and future plans. Here’s a quick cheat sheet:
| Use Case | Recommended API |
| Simple CRUD app | REST |
| Bandwidth-sensitive or Mobile | GraphQL |
| Microservices Communication | gRPC |
| Real-time app | WebSockets |
| Legacy/Enterprise system | SOAP |
| Quick prototyping | Serverless (API Gateway) |
Regardless of what architecture you use, testing should never be an afterthought. That’s where tools like Keploy.io come in. They support modern API styles, generate tests from real traffic, and make debugging a breeze.
So go ahead, choose the right API style — and don’t forget to test it smartly.
Read more on - https://keploy.io/blog/community/a-guide-to-various-api-architectures