Making HTTP Requests

An API (Application Programming Interface) lets programs talk to each other; most web APIs work over HTTP. The standard way to make HTTP requests in Dart and Flutter is the http package.

dart pub add http

A GET request

import 'dart:convert';
import 'package:http/http.dart' as http;

class Repo {
  final String fullName;
  final int stars;
  Repo(this.fullName, this.stars);

  factory Repo.fromJson(Map<String, dynamic> json) =>
      Repo(json['full_name'] as String, json['stargazers_count'] as int);
}

Future<Repo> fetchRepo(String name) async {
  final response = await http
      .get(Uri.https('api.github.com', '/repos/$name'))
      .timeout(const Duration(seconds: 10));

  if (response.statusCode != 200) {
    throw Exception('Request failed: ${response.statusCode}');
  }
  return Repo.fromJson(jsonDecode(response.body) as Map<String, dynamic>);
}

Future<void> main() async {
  final repo = await fetchRepo('dart-lang/sdk');
  print('${repo.fullName} has ${repo.stars} stars');
}

dart-lang/sdk has 10734 stars

(The number will be different when you run it.)

• Uri.https(host, path) builds the address and encodes it correctly.
• Always set a timeout, so a slow server can't hang your app.
• A 404 or 500 is a normal response, not an exception — check statusCode yourself.
• Network failures (no connection) throw exceptions such as SocketException / ClientException; catch them where you can show a helpful message.

POST with JSON

final response = await http.post(
  Uri.https('httpbin.org', '/post'),
  headers: {'Content-Type': 'application/json'},
  body: jsonEncode({'title': 'Hello'}),
);
print(response.statusCode);

Beyond the basics

For larger apps, the dio package adds interceptors (for example, adding an auth token to every request), retries, and upload progress.

Common mistakes

• Hard-coding API keys in app code — anything shipped in an app can be extracted. Keep secrets on a server.
• Parsing the body without checking the status code first.