Different types of API and full form of API ?

Overview

API stands for Application Programming Interface — a set of rules and protocols that allows one software application to communicate with another.

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Full Form

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API = Application Programming Interface

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Types of APIs

1. REST API (Representational State Transfer)

Most common type — uses HTTP methods over the web.

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// REST API in Flutter
final response = await http.get(
  Uri.parse('https://api.example.com/users'),
  headers: {'Authorization': 'Bearer $token'},
);

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2. GraphQL API

Query-based API — request exactly the data you need.

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# Single query gets nested data
query {
  user(id: "1") {
    name
    email
    orders { id, total }
  }
}

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3. gRPC API (Google Remote Procedure Call)

Binary protocol using Protocol Buffers — high performance.

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

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4. WebSocket API

Persistent bidirectional real-time communication.

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final channel = WebSocketChannel.connect(Uri.parse('wss://api.example.com/ws'));
channel.stream.listen((message) => print(message));
channel.sink.add('Hello');

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5. SOAP API (Simple Object Access Protocol)

XML-based, enterprise legacy systems.

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<soap:Envelope>
  <soap:Body>
    <GetUser><userId>1</userId></GetUser>
  </soap:Body>
</soap:Envelope>

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6. Webhook API

HTTP callback — server pushes data to your endpoint.

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Payment complete → Stripe POSTs to your /webhook endpoint

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7. Library/SDK API

APIs within a programming language (not over network).

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// Flutter's own API
Text('Hello') // Using Flutter widget API
SharedPreferences.getInstance() // Plugin API

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API Comparison

Summary: API is the contract between two systems. REST is the most common for mobile apps. gRPC for performance-critical services. WebSocket for real-time. GraphQL for flexible queries.