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Choose based on how your application handles work: WebClient is Spring’s non-blocking client for reactive composition, high concurrency, and streaming; RestTemplate makes blocking calls and remains workable in stable imperative applications. For new synchronous code, also consider RestClient, Spring’s modern fluent blocking client.
RestTemplate vs. WebClient at a glance
| Area | RestTemplate | WebClient |
|---|---|---|
| Execution model | Synchronous and blocking: the calling thread waits for the request to complete. | Non-blocking and reactive, built around Reactor types; supports asynchronous composition. |
| Typical fit | Imperative applications, especially existing code where stability and migration cost favor keeping it. | Reactive applications and use cases involving asynchronous work, high concurrency, or streaming. |
| API style | Template-method API with convenience methods, plus exchange and execute. |
Functional, fluent API for composing requests and reactive processing. |
| Streaming | Not the recommended choice for asynchronous or streaming scenarios. | Supports streaming uploads and downloads. |
| Current status | Deprecated in favor of RestClient in Spring Framework 7.0. | Spring WebFlux’s reactive HTTP client. |
The status note reflects current Spring documentation; check the documentation for the Spring Framework version your application uses, since deprecation guidance can change between releases.
How the execution models differ
RestTemplate blocks the calling thread
A RestTemplate request runs synchronously: the thread making the call waits while the client communicates with the server and receives a response. That model can be straightforward in imperative code, where request handling is already organized as sequential work.
WebClient is non-blocking and composable
WebClient is designed to avoid tying up a calling thread while waiting for network I/O. Its Reactor-based API lets you compose asynchronous operations and supports reactive back pressure. Spring describes it as a fluent, non-blocking client; it can also be used in Spring MVC applications when appropriate, not only in applications built on WebFlux.
The Tool Desk
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Concurrency, performance, and streaming
WebClient’s non-blocking design is intended to handle high concurrency with fewer hardware resources than a blocking approach. That is a qualitative architectural benefit, not a guarantee that every WebClient application will be faster. The official sources cited here publish no controlled RestTemplate-versus-WebClient latency or throughput comparison.
Rank #2
Actual performance depends on the workload, client connector, server behavior, connection pooling, and whether the rest of the application can use reactive processing. If your application is otherwise imperative and makes a modest number of calls, the benefits of moving to WebClient may not outweigh the added reactive programming model.
For streaming uploads or downloads, WebClient is the more suitable choice. Spring’s RestTemplate Javadoc specifically advises considering WebClient for asynchronous and streaming scenarios.
What changes if you choose RestClient?
RestClient is Spring’s modern synchronous, fluent HTTP client for new blocking code. Spring introduced it in Framework 6.1 and positions it as the successor to RestTemplate. It shares request factories, interceptors, initializers, and message converters with RestTemplate, which can ease migration of existing client configuration.
RestTemplate is deprecated in favor of RestClient in Spring Framework 7.0. That does not mean every existing RestTemplate integration needs immediate replacement: weigh the framework version, maintenance horizon, and cost of changing stable code. For a new synchronous integration, evaluate RestClient rather than starting with RestTemplate.
Quick Recap
Best Value
Rank #4
Which client should you use?
- Choose WebClient when you need reactive composition, non-blocking I/O, streaming, or an architecture designed to handle many concurrent requests efficiently.
- Keep RestTemplate when it is already stable in an imperative application and migration offers little practical benefit.
- Evaluate RestClient for new synchronous code or when modernizing a blocking client without adopting a reactive model.
Official Spring documentation
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