REST vs GraphQL vs gRPC: Which API to Choose for Your Product

Choosing a protocol for client-server interaction has long ceased to be a minor technical detail. It determines the speed of iterations, the ease of maintaining mobile applications, and the manageability of contracts as the product grows. Clear scenarios have formed around the three major paradigms — REST, GraphQL, and gRPC — where each provides maximum benefit. In this article, we examine them from a practical perspective: how the contract is formed, what happens with versioning, and how suitable the solution is for mobile environments. At the end, we will provide recommendations focused on real-world custom development.

REST: Contracts and Versioning

REST remains the most common way to organize APIs, especially for web applications and public services. Its contract is built around resources and HTTP methods: GET, POST, PUT, DELETE. Descriptions of endpoints are typically fixed in an OpenAPI specification (Swagger), which serves as both documentation and a source for generating client code. For mobile teams, this means the contract can be conveyed with almost no additional communication — and that's valuable when distributed teams work on the product. For example, when developing web applications and public APIs, we at ESK Solutions always start by agreeing on the OpenAPI schema before writing code.

Versioning in REST is one of the most painful topics. Common approaches include a prefix in the URI (/v1/orders), a custom header Accept-version, or query parameters. Each forces you to maintain multiple parallel implementations, which blows up the test volume and can lead to hidden logic duplication. On mobile clients, this effect is amplified: forced API version updates may require an urgent app release that hasn't yet gone through the full review cycle in stores. At the same time, REST offers a plus for mobile teams — support for standard HTTP caching. Properly configured ETag and Cache-Control headers reduce battery drain and traffic on repeated calls, directly impacting user experience.

GraphQL: Query Flexibility and Schema Evolution

GraphQL offers a different philosophy: the client requests exactly the fields it needs at that moment. The contract is described by a single strongly typed schema, rather than dozens of endpoints. This model is especially advantageous on mobile devices, where the amount of data transferred is critical and rendering speed often depends on response size. Instead of multiple requests for related entities (common in REST), GraphQL allows you to fetch the entire required structure in one call — drastically reducing the number of round trips and noticeably improving the perceived responsiveness of the interface.

As for versioning — GraphQL is often positioned as a versionless protocol. API evolution happens by adding new fields and types without removing old ones; deprecated fields are marked with the @deprecated directive. This simplifies life for the API publisher, but shifts responsibility to the mobile development team: they need to monitor warnings and refactor queries in a timely manner. Moreover, the lack of strict versioning means that schema errors can immediately affect all clients. Therefore, GraphQL requires discipline in schema design and well-thought-out monitoring tools. We often apply this approach when creating SaaS products, where high data customization and frequent interface iterations are important.

gRPC: Strict Contract and Performance

gRPC relies on Protocol Buffers — a binary serialization format with a strict schema. The contract is described in .proto files, from which client and server stubs are automatically generated in multiple languages. This means any discrepancy between client and server is caught at compile time, not at runtime. For microservice architectures, such a contract almost eliminates misunderstandings between teams and significantly speeds up integration. We actively use gRPC in projects involving high-load cloud services — for example, when developing cloud solutions, where minimal latency is critical.

Versioning in gRPC is implemented through protobuf compatibility rules: adding fields without changing indices and removing them with reservation. This allows releasing backward-compatible changes without coordinating releases. However, strict typing can become burdensome when rapid prototyping is required. For mobile clients, the situation is twofold. Native iOS and Android apps can use gRPC clients directly and gain a massive advantage in speed and traffic volume, which is especially noticeable with data streaming. Yet gRPC-Web — the browser intermediary — still has limitations (not all streaming types are supported), and embedding it in mobile web views requires additional configuration. Therefore, for purely mobile solutions, gRPC is often supplemented with a REST gateway automatically generated from the same .proto file.

Comparing Approaches for Mobile Development

To choose the right tool, it's helpful to compare key metrics. Below is a summary table focused specifically on mobile projects.

The figures and comparisons provided are illustrative, not project-specific data. For accurate benchmarks, testing on a real stack is required.

How to Choose an API for Your Product

Base your decision on three vectors: iteration speed, data consumer types, and architectural constraints.

• If you have a public API or multiple heterogeneous clients, REST with an OpenAPI contract offers the best balance between simplicity and predictability. Especially if the mobile part already uses proven HTTP libraries. You can discuss such an architecture as part of our web application and API development service — we help design a schema that will last for years.
• When UX and data customization per screen are critical (e.g., a mobile app with complex dashboards), GraphQL is the natural choice. It's worth investing upfront in schema monitoring and query analysis tools. For teams building multi-user platforms, SaaS development with GraphQL on the backend is relevant.
• For high-performance microservices, machine-to-machine interaction, and real-time data, gRPC is indispensable. If you plan a scalable cloud environment or integration with mobile IoT devices, see how it fits into cloud development. In scenarios requiring fast exchange between CRM backends and internal services, gRPC is also justified — we often use it in CRM creation and integration.
• Hybrid solutions are not uncommon. For example, the main API is built on GraphQL for mobile and web clients, while inter‑system calls are implemented using gRPC. This approach satisfies both frontend teams and backend engineers, maintaining a single contract. When building complex internal ecosystems, we often use hybrids, including for corporate portals and intranets, where some data may be accessible via WebSockets and some via REST.

Whatever the choice, the key to success is the immutability of the contract for already published versions and a well-thought-out strategy for deprecating features. Otherwise, any protocol will quickly become technical debt.

Frequently Asked Questions

Can GraphQL and gRPC be used together in the same project?

Yes, this is a common architecture. For example, the external API for mobile applications is provided via GraphQL for query flexibility, while internal service-to-service communication uses gRPC for speed. A BFF layer (Backend For Frontend) can sit between them, converting gRPC responses into GraphQL entities.

How does REST solve the over-fetching problem on mobile devices?

Standard REST does not fully solve it, because the client receives all fields of the resource. For mobile clients, partial responses are used via parameters like ?fields=name,price (Sparse Fieldsets), but this depends on the server implementation and is not part of the specification. An alternative is to adopt GraphQL where data over-fetching is critical.

Is a forced update of the mobile app required when the API changes?

It depends on the versioning strategy. When using REST with a version prefix, old clients can continue to work with /v1 until support is discontinued. In GraphQL, adding fields does not break old queries. In gRPC, protobuf backward compatibility helps avoid forced updates if schema change rules are followed. In all cases, it's important to monitor traffic and plan deprecation windows.

Which protocol is best for a mobile app MVP?

For quick prototyping, teams often choose GraphQL (especially with code generation from the schema) or simple REST based on OpenAPI — both allow fast iteration without strict compilation. gRPC can be overkill at the start if there are no high performance requirements or strict contracts between multiple teams.

API design is not a one-time event but a process that extends throughout the entire product lifecycle. A well-chosen and implemented approach reduces the cost of changes, simplifies mobile client support, and makes technical contracts a reliable foundation rather than a source of conflicts. If you are planning a new product or updating your current stack, ESK Solutions experts can help you choose the architecture and bring it to code.