Feign allows you to abstract the mechanics of calling a REST service. Once you configure and annotate the Feign interface, you can call a REST service by making a simple Java function call. The actual implementation of making a REST call is handled at runtime by Feign. This means that the implementation can be configured without changing your business logic code.

By just changing the Feign configuration in Java or using properties you can add encoding/decoding, logging, and change the REST call implementation library. All this is done through configuration only, while the business logic that calls the service remains unchanged.

Since Feign uses standard Java interfaces, it's also easy to mock them during unit tests.

There was an issue in feign client before. I guess you are experiencing the same maybe because you are using an old version but what you should do is including the pathVariable name in your @PathVariable annotation like this @RequestMapping(value = "/hello/{name}", method = RequestMethod.GET) String hello(@PathVariable(value = "name") String name);

You can find the details from here