HATEOAS with gRPC: Is It Possible? (And Should You Do It?)

Eleftheria DrosopoulouMay 16th, 2025Last Updated: May 13th, 2025

0 260 3 minutes read

HATEOAS (Hypermedia As The Engine Of Application State) is a REST constraint that guides clients through application states using hypermedia links. It’s a staple of RESTful API design. But what happens when you move away from HTTP-based REST to a high-performance RPC protocol like gRPC?

Can you still use HATEOAS principles with gRPC? And more importantly—should you?

Let’s dive into what HATEOAS is, how gRPC works, and whether it makes sense (or not) to combine them.

🔍 What is HATEOAS, Really?

HATEOAS is one of the REST maturity levels described by Roy Fielding. It allows clients to interact with the application entirely through hyperlinks provided dynamically by the server. This means:

Clients don’t need to hard-code URIs.
The server guides the client through valid state transitions.
Clients become loosely coupled and more adaptable to change.

A typical HATEOAS response looks like this in REST:

{
  "orderId": 123,
  "status": "SHIPPED",
  "_links": {
    "self": { "href": "/orders/123" },
    "cancel": { "href": "/orders/123/cancel" }
  }
}

Now, contrast that with how gRPC works.

⚙️ What is gRPC?

gRPC is a high-performance, contract-first Remote Procedure Call (RPC) framework developed by Google. It uses Protocol Buffers (Protobuf) for serialization and HTTP/2 as the transport layer.

Instead of exchanging self-descriptive hypermedia documents, gRPC is all about calling methods on a service:

service OrderService {
  rpc GetOrder(OrderRequest) returns (OrderResponse);
  rpc CancelOrder(OrderCancelRequest) returns (OrderResponse);
}

gRPC is excellent for:

High-throughput microservices
Streaming data
Strong typing
Cross-language communication

But it lacks any native concept of hypermedia or dynamic link traversal.

🧠 Can You Implement HATEOAS in gRPC?

Technically? Yes.
Practically? Rarely recommended.

Let’s break down how you could simulate HATEOAS in gRPC.

✅ Option 1: Include Link Metadata in Responses

You could define Protobuf messages with optional link fields:

message OrderResponse {
  int32 orderId = 1;
  string status = 2;
  repeated Link links = 3;
}

message Link {
  string rel = 1;
  string href = 2;
}

This mimics HATEOAS by embedding a list of available actions for the client.

But here’s the problem: href in gRPC doesn’t make sense. Clients don’t follow URLs—they call methods.

To adapt this idea, you’d need to:

Treat href as a method name or action key
Implement a client that can interpret those instructions
Handle versioning and dynamic method dispatch

This is more like custom protocol semantics, not true HATEOAS.

⚠️ Option 2: Action Envelopes or “Next Operations”

Some have experimented with action-oriented envelopes in gRPC responses:

message Action {
  string name = 1;     // e.g., "cancel"
  string endpoint = 2; // Optional - could be internal
  map<string, string> parameters = 3;
}

This could help simulate state transitions, but now your clean gRPC API becomes cluttered with business logic metadata—not ideal.

❌ Why gRPC and HATEOAS Don’t Mix Well

Here’s why trying to marry HATEOAS and gRPC often creates more problems than it solves:

HATEOAS (REST)	gRPC
Hypermedia-driven	Method-driven
Loose coupling via URIs	Tight coupling via method contracts
Runtime-discoverable	Compile-time discoverable
Text-based (usually JSON/XML)	Binary Protocol Buffers
HTTP verbs & URLs	RPC endpoints over HTTP/2

The whole point of HATEOAS is runtime navigation. The whole point of gRPC is strict, pre-defined contracts.

Trying to combine them often means fighting the grain of both systems.

✅ When You Might Want HATEOAS-Like Features in gRPC

That said, there are edge cases where HATEOAS-like behavior in gRPC might make sense:

Dynamic Workflows
If your gRPC service guides the client through multi-step flows (e.g., state machines), you could use an action map to indicate next steps.
Client-Orchestrated Logic
In some mobile or desktop clients, if you want to expose available actions per resource without hard-coding logic, embedded instructions could help.
API Gateways Translating REST to gRPC
If you expose a HATEOAS-rich REST layer in front of gRPC microservices, the gateway can handle the hypermedia logic.

But even in these cases, it’s often better to define workflows explicitly or use an orchestration engine.

🤔 Should You Do It?

In most cases: No.

gRPC is not built for HATEOAS. It’s optimized for performance, streaming, and strong contracts—not self-discovery.

If your use case relies heavily on hypermedia and dynamic navigation:

Stick with REST + HATEOAS
Or use GraphQL for runtime discoverability
Or separate your “discovery” from your “execution”

🔗 Additional Resources

gRPC Official Site
Richardson Maturity Model – for REST level definitions
REST vs gRPC: When to Use Which
Protocol Buffers

🧵 Conclusion

HATEOAS is powerful—but only when applied in the right context. gRPC isn’t that context. While you can technically mimic hypermedia by embedding action metadata, this undermines gRPC’s strengths and leads to awkward, overly complex APIs.

Use the right tool for the job: