REST vs GraphQL

REST and GraphQL run over standard HTTP/HTTPS protocols using network ports 80 (HTTP) or 443 (HTTPS). However, they utilize HTTP methods very differently.

    REST uses standard HTTP verbs semantically: It maps CRUD operations to HTTP methods over multiple URLs:

• GET /api/v1/devices => Fetch list
• POST /api/v1/devices => Create new
• PUT /api/v1/devices/12 => Update
• DELETE /api/v1/devices/12 => Delete

    GraphQL usually operates over a single POST endpoint: It typically uses a single URL (e.g., [https://api.example.com/graphql](https://api.example.com/graphql)).

• Whether you are fetching data (a query) or modifying data (a mutation), you send an HTTP POST request to that single endpoint. 
• The query payload sits inside the JSON request body.

The primary difference between REST and GraphQL lies in how data is delivered: REST organizes data around fixed, server-defined resource URLs, while GraphQL uses a single endpoint that allows the client to request exactly the data it needs. GraphQL more flexible in returning specific attributes.

1. REST (Fixed Payload): When you call a REST endpoint like GET /users/101, the backend server controls what fields are returned. If the user object contains 50 attributes (address, history, preferences, metadata), you receive all 50 attributes - even if your mobile screen only needs the first_name.
2. GraphQL (Client-Driven Payload): The frontend client specifies exact attributes in the request payload. The server returns a JSON response that mirrors the structure of the request.

Fundamental differences:

Feature	REST (Representational State Transfer)	GraphQL
Core Concept	Architectural style based on resources.	Query language and runtime based on a schema.
Endpoints	Multiple endpoints (e.g., /users, /posts/42).	Single endpoint (typically /graphql).
Data Fetching	The server defines the response payload.	The client specifies the exact fields it needs.
Over/Under-fetching	Common (returns either too much or requires multiple requests).	Eliminated (requests only desired fields in one round trip).
Caching	Out-of-the-box using standard HTTP status codes and headers (CDNs, browsers).	Complex (requires specialized client-side normalized caches like Apollo/URQL).
Error Handling	Standard HTTP status codes (200, 404, 500, etc.).	Always returns HTTP 200 OK; errors are detailed inside an errors array in the JSON payload.
Versioning	Typically handled via URLs or headers (e.g., /v1/users, /v2/users).	Versionless; non-breaking schema evolution by adding or deprecating fields.

REST vs GraphQL selection:

Choose REST when:

• Building Public or Third-Party APIs: Standard HTTP mechanisms make it easy for external developers to consume without specialized tooling.

• Heavy Caching Requirements: Ideal for applications that rely heavily on edge caches, CDNs, or browser-level caching (e.g., static content delivery, e-commerce product catalogs).

• Simple CRUD Operations: Resource-centric applications with simple data models (Create, Read, Update, Delete) are faster to implement with standard REST frameworks.

• File Uploads & Streaming: Standard HTTP multipart data handling is much simpler in REST.

• Microservice Boundaries: Excellent for inter-service communication where endpoints have strict, isolated domains.

Choose GraphQL when:

• Complex/Nested Data Relationships: When a single UI view requires data stitched together from multiple database tables or services (e.g., social media feeds, dashboards).

• Mobile & Low-Bandwidth Applications: Eliminates over-fetching over slow mobile networks, saving cellular data and battery life.

• Multi-Client Platforms: When web, iOS, Android, and smart devices consume the same backend but require completely different fields or layouts.

• Rapid UI Iteration: Frontend teams can request new attributes from the existing schema without waiting for backend engineers to build a new endpoint.

• Real-time Data: Native support for event-driven updates via GraphQL Subscriptions (over WebSockets).

GraphQL is heavily favored in these domains:

• Social Media, Streaming, and Content Platforms (examples: Meta, Netflix, Twitter)
• E-Commerce and Omnichannel Retail (examples: Shopify, Target, Walmart)
• Enterprise Microservice Organizations (Fintech, SaaS, Telco) (examples: GitHub, GitHub, Intuit)

Why is not Everyone Using GraphQL?
While GraphQL excels at client flexibility and data aggregation, REST remains dominant in:

1. Public/Third-Party Partner APIs: REST is easier to document, rate-limit, and enforce strict usage contracts on third parties.
2. Simple CRUD Microservices: Internal microservice-to-microservice communication where HTTP caching, gRPC, or lightweight REST is simpler to implement.
3. Caching Simplicity: Standard REST APIs leverage off-the-shelf edge networks and CDNs (Cloudflare, Fastly) using standard HTTP caching headers (Cache-Control) natively, whereas GraphQL requires query-level caching strategies.