By Diego Liascovich

*Full-Stack Developer | Microservices | Api | Rest | GraphQL

APIs are the backbone of modern applications — but not all APIs are created equal. In this post, I’ll walk you through the most common types of APIs: REST, GraphQL, Event-Driven APIs, gRPC, and more — explaining how they work, their pros and cons, and when to use each.

🌐 1. REST (Representational State Transfer)

📌 Overview

REST APIs use standard HTTP verbs (GET, POST, PUT, DELETE) to access resources via URLs.

✅ Best For

• CRUD applications
• Simple and predictable data access
• Public APIs

🧪 Example

GET /api/users/42

✔️ Pros

• Easy to understand and implement
• Widely supported by tools and frameworks
• Can be cached via HTTP

❌ Cons

• Overfetching/underfetching of data
• Multiple requests needed to fetch related data

🧬 2. GraphQL

📌 Overview

GraphQL uses a single endpoint and a query language that lets clients request exactly the data they need.

✅ Best For

• Complex UIs that need different data shapes
• Frontend-heavy apps (like React/Angular)
• Reducing number of API calls

🧪 Example

query {
  user(id: "42") {
    name
    email
    orders {
      id
      total
    }
  }
}

✔️ Pros

• Precise data retrieval (no overfetching)
• Strongly typed schema
• One endpoint for all data

❌ Cons

• Harder to cache with standard HTTP tools
• Learning curve for query language
• Complex server setup for some use cases

⚡ 3. Event-Driven APIs (EDA)

📌 Overview

Instead of calling APIs directly, services emit events (like order.placed) that other services subscribe to.

✅ Best For

• Microservices architecture
• Loose coupling between services
• Asynchronous flows (notifications, logs, automation)

🧪 Example Event

{
  "event": "user.created",
  "data": {
    "userId": "123",
    "email": "user@example.com"
  }
}

✔️ Pros

• Fully decoupled services
• Highly scalable and resilient
• Ideal for audit logs, triggers, and workflows

❌ Cons

• Harder to debug and trace flow
• Requires messaging infrastructure (e.g., RabbitMQ, Kafka)

🧠 4. gRPC (Google Remote Procedure Call)

📌 Overview

gRPC is a high-performance RPC framework using Protocol Buffers and HTTP/2.

✅ Best For

• Microservices with high throughput needs
• Internal service-to-service communication
• Real-time streaming

🧪 Example (Proto)

service UserService {
  rpc GetUser (UserRequest) returns (UserResponse);
}

✔️ Pros

• Extremely fast and lightweight
• Language-neutral, auto-generates code
• Built-in streaming support

❌ Cons

• Not browser-friendly by default
• Requires .proto file management
• More complex debugging

📡 5. WebSockets

📌 Overview

WebSockets provide bi-directional communication between client and server, ideal for real-time applications.

✅ Best For

• Chat apps
• Live dashboards/notifications
• Collaborative tools

✔️ Pros

• Low latency, real-time data
• Two-way persistent connection

❌ Cons

• More complex server/client handling
• Can’t use REST-style caching

🧓 6. SOAP (Simple Object Access Protocol)

📌 Overview

An older protocol using XML with a strict message format.

✅ Best For

• Legacy systems (banks, governments)
• Strong contract-based APIs

✔️ Pros

• Rigid structure and strong typing
• Works well in enterprise environments

❌ Cons

• Verbose XML
• Slower and more complex than REST/GraphQL

📊 Quick Comparison

✅ Conclusion

There’s no “one size fits all” — choose your API type based on:

• 🚀 Performance needs
• 📦 System architecture
• 🔄 Data patterns (real-time, on-demand, batch)
• 🔧 Development environment

💬 What API style do you prefer and why? Share your experience below!

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