Boost Your Java API Testing with IntelliJ IDEA’s Built‑in HTTP Client

Java backend developers often need to test many Controller APIs. Instead of switching to external tools like Postman, you can use IntelliJ IDEA’s built‑in HTTP Client plugin to test requests directly within the IDE.

HTTP Client Introduction

The HTTP Client plugin, available from the JetBrains plugin marketplace, lets you create, edit, and execute HTTP requests right in the code editor.

After installing the plugin, any method annotated with @RequestMapping, @GetMapping or @PostMapping shows a small icon. Clicking the icon opens a .http file where you can define all requests for that controller.

In the .http file, click the green play button next to any request to execute it.

All .http files are stored under Scratches and Consoles → Scratches. You can create multiple files to separate different modules, similar to Postman collections.

The top‑left button lets you add various request types (GET, POST with different parameter forms, GRPC, WebSocket, etc.).

Tip: For POST requests with many parameters, install a “POJO to JSON” plugin. Right‑click a parameter object and choose Copy Json to generate a ready‑to‑use JSON payload.

You can also define environment files (e.g., dev and test) and select the appropriate environment for each request.

Importing Postman collections is supported via the “Import from Postman Collections” plugin, which converts Postman requests into HTTP Client format with a single click.

You can also specify the HTTP protocol version (e.g., HTTP/2) at the end of a request line, and paste curl commands to auto‑convert them to HTTP Client syntax.