Introduction

Retrofit turns your HTTP API into a Java (or Kotlin) interface.

public interface GitHubService {
  @GET("users/{user}/repos")
  Call<List<Repo>> listRepos(@Path("user") String user);
}

The Retrofit class generates an implementation of the GitHubService interface.

Retrofit retrofit = new Retrofit.Builder()
    .baseUrl("https://api.github.com")
    .build();

GitHubService service = retrofit.create(GitHubService.class);

Each Call from the created GitHubService can make synchronous or asynchronous HTTP requests to the remote webserver.

Call<List<Repo>> repos = service.listRepos("octocat");

Use annotations to describe the HTTP request on each interface method:

• URL parameter replacement and query parameter support
• Object conversion to request body (e.g., JSON, protocol buffers)
• Multipart request body and file upload