There's a version of this conversation that happens in engineering teams everywhere. Someone suggests gRPC. Someone else says REST works fine. The tech lead Googles 'gRPC vs REST,' finds an article full of tables and bullet points, and the team carries on doing what they were already doing.
That's not entirely wrong. REST is the backbone of the modern web, reliable, well-understood, and practically universal. But the conversation is worth having properly, because the difference between these two API architectures isn't just technical. It's a design decision that affects how fast your system runs, how easy it is to maintain, and how much your team will curse it six months from now.
According to Postman's 2025 State of the API Report, 93% of software teams use REST APIs in some capacity. gRPC sits at 14%. That gap tells you something, not that REST is better, but that it has a 20-year head start and a much lower barrier to entry. The real question isn't which one is more popular. It's which one is right for what you're building.
Let's get into it.
First, What Are They Actually Doing?
Before comparing them, it helps to understand what problem each one was designed to solve, because they come from genuinely different philosophies.
REST — Representational State Transfer — was formalised in 2000 by Roy Fielding in his doctoral dissertation, and it became the architecture that powered the explosion of web APIs. The core idea is elegant: the internet already has a protocol (HTTP), resources have addresses (URLs), and a small set of verbs — GET, POST, PUT, DELETE — can describe nearly anything you'd want to do to a resource. REST speaks the language of the web because it was designed to.
gRPC is a different animal. Google built it in 2015 to solve a specific internal problem: their systems needed to talk to each other at enormous speed and scale across multiple programming languages. So instead of asking a resource to change, gRPC lets one system call a function directly on another, like reaching into a remote server and running code. It uses HTTP/2 under the hood and a compact binary format called Protocol Buffers (Protobuf) instead of JSON.
REST speaks the language of the web. gRPC speaks the language of distributed systems. They're good at different things because they were built for different things.
The Performance Question and Why It's More Complicated Than It Looks
The performance argument for gRPC is real. The numbers are not subtle.
A 2025 benchmark study found that gRPC demonstrated 19% lower CPU usage, 34% lower memory consumption, and 41% lower network bandwidth requirements under equivalent load conditions. Real-world latency measurements show REST averaging around 250ms, while gRPC delivers closer to 25ms for real-time workloads. And for throughput: gRPC can handle approximately 50,000 requests per second on production-grade hardware, compared to around 20,000 for REST.
That's not a small difference. At scale, those gaps become significant, in infrastructure costs, in user experience, in how many servers you need to keep the lights on.
But here's the thing that benchmark articles usually bury in a footnote: synthetic benchmarks often exaggerate differences that have little impact in production. Real-world performance depends far more on system architecture, payload design, and network conditions than on the protocol itself. For most applications, the few milliseconds saved per call go completely unnoticed.
The honest version of the performance question isn't 'which one is faster?' It's 'does the speed difference matter for what I'm building?' For a public-facing CRUD API that powers a web dashboard, probably not. For a financial system processing hundreds of thousands of real-time transactions per second, absolutely.
gRPC is faster. But faster only matters when speed is actually your bottleneck. And most of the time, it isn't.
Under the Hood: Where the Real Differences Live
The performance gap exists for a reason, and understanding it helps you make a better decision.
REST typically runs on HTTP/1.1 and transmits data as JSON, text-based, human-readable, and easy to debug in any browser. Every request opens a new connection. Every response is a fresh exchange. It's simple, which is why it's everywhere.
gRPC runs on HTTP/2, which changes the game in three meaningful ways. First, it multiplexes, multiple requests can travel over a single connection simultaneously, instead of queuing up one at a time. Second, it streams — both the client and the server can send multiple messages across a single open connection, which means you can build genuinely real-time systems without hacks like long polling. Third, the data format (Protobuf) is binary, not text, which makes it significantly faster to serialise and deserialise, and considerably smaller over the wire.
There's a trade-off, though. Binary data is not human-readable. You can't open a gRPC response in your browser and see what's happening. Debugging requires specialised tools. And the tightly coupled nature of gRPC, both client and server must share the same .proto file that defines the data structure, means that a schema change requires updates on both ends. REST's loose coupling, where client and server operate independently of each other's internals, is genuinely easier to evolve over time.
The Communication Model Nobody Talks About Enough
One of gRPC's most underappreciated advantages is its support for four distinct communication models, and only one of them maps to what REST can do.
REST is unary: one request, one response, every time. That's fine for most things.
gRPC supports unary too, but it also supports server-side streaming (one request, a continuous flow of responses), client-side streaming (a continuous flow of requests, one response), and bidirectional streaming (both sides sending and receiving simultaneously over a single connection). That last one is particularly powerful for real-time applications, think live dashboards, multiplayer games, collaborative editing tools, or any system where both parties need to react to each other continuously.
Building real-time features on REST requires workarounds, WebSockets, long polling, server-sent events. They work, but they add complexity. gRPC bakes this capability in from the start.
Who Actually Uses What — and What That Tells You
The most illuminating thing you can look at isn't the benchmark data. It's what companies have actually chosen to build with.
Amazon S3 and eBay, two of the most heavily trafficked systems on the internet, run on REST. eBay's REST APIs handle hundreds of millions of API calls per hour, powering product listings, searches, and transactions for buyers, sellers, and third-party developers worldwide. The architecture that works for them is open, accessible, and compatible with virtually anything.
Netflix, on the other hand, migrated several of its internal microservices from REST to gRPC and reported meaningful performance improvements. Google uses gRPC extensively across its own distributed infrastructure. Internally-facing systems, where performance is everything and external compatibility is irrelevant, are where gRPC earns its keep.
The pattern is consistent: REST for external-facing, public, or partner-facing APIs. gRPC for internal, high-performance, high-volume systems where the teams on both ends of the connection are yours to coordinate.
How to Actually Decide
Strip away the benchmarks and the philosophy, and the decision usually comes down to a handful of honest questions.
Use REST when:
You're building a public API that external developers or partners will consume. Simplicity, discoverability, and accessibility matter more than raw performance. Your team is more familiar with REST and the project timeline is tight. You're working with web browsers directly, where gRPC has limited native support. The data you're exchanging is relatively simple and not latency-critical.
Use gRPC when:
You're building internal microservices that need to talk to each other at high speed and volume. Real-time or streaming communication is a core requirement, not a nice-to-have. Your system spans multiple programming languages and you want consistent, generated client code across all of them. You're operating in bandwidth-constrained environments like IoT or mobile backends where Protobuf's compact size matters. Performance is a genuine bottleneck, not a theoretical concern.
Use both when:
Most mature systems don't choose one or the other, they use both. REST for the customer-facing layer; gRPC for the internal service-to-service communication underneath it. The two architectures are not mutually exclusive, and hybrid approaches are increasingly the norm in serious engineering organisations.
The best architecture isn't the fastest one or the simplest one. It's the one your team can build reliably, reason about clearly, and evolve without dread.
The Verdict
REST isn't going anywhere. It powers the vast majority of the web and will continue to for the foreseeable future. Its simplicity, its universality, and its compatibility with every browser and client imaginable make it the right default for most projects.
gRPC is not a replacement for REST. It's an answer to a specific set of problems, high-performance internal systems, real-time communication, polyglot microservice architectures, that REST was never designed to solve particularly well.
The mistake isn't choosing one over the other. The mistake is choosing without thinking. 93% of teams use REST, but the most performance-critical infrastructure in the world runs on gRPC. Both facts can be true at the same time, because they're solving different problems.
Know what you're building, know what you need, and pick the tool that serves the work, not the one that wins the argument.
