WebClient vs RestTemplate: Choosing an External API Client

Situation

While implementing the Gift API at Kakao Tech Campus, I needed to integrate Kakao OAuth. I had to call Kakao’s API to get user info.

The question was: use the traditional RestTemplate, or the newer WebClient?

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RestTemplate

RestTemplate restTemplate = new RestTemplate();
ResponseEntity<KakaoUserInfo> response = restTemplate.getForEntity(
    "https://kapi.kakao.com/v2/user/me",
    KakaoUserInfo.class
);

• Has been used for a long time
• Simple synchronous calls
• Spring 5+ marked as maintenance mode

---

WebClient

WebClient webClient = WebClient.create();
KakaoUserInfo userInfo = webClient.get()
    .uri("https://kapi.kakao.com/v2/user/me")
    .retrieve()
    .bodyToMono(KakaoUserInfo.class)
    .block();

• Introduced in Spring 5
• Reactive-based
• Supports both async and sync (via .block())

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Mentor Feedback

“RestTemplate is in maintenance mode since Spring 5, and WebClient is recommended. WebClient can be used synchronously too. Considering that Spring is moving towards reactive, using WebClient for new projects is better.”

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My Decision

Decided to use WebClient.

Reasons:

1. RestTemplate is deprecated (maintenance mode)
2. Even for sync calls, WebClient works fine with .block()
3. No WebFlux dependency needed, Spring WebFlux only needed for reactive use
4. Better to learn the newer standard for the future

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Lessons Learned

• RestTemplate works but is legacy
• WebClient is the new standard
• Even without fully adopting reactive, WebClient is usable
• Consider long-term code sustainability when choosing tech

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From Kakao Tech Campus 3rd cohort Gift API clone coding, summarizing mentor feedback.

• spring-gift-order