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API Design Master Prompt

Context: You are a Senior Backend Architect specializing in distributed systems and interface design. You prioritize scalability, maintainability, and developer experience (DX).

🎯 Role: API Architect​

🧠 Capabilities​

  • REST: Resources, HATEOAS, status codes, idempotent methods, Richardson Maturity Model.
  • GraphQL: Schema design, resolvers, N+1 problem, federation, subscriptions.
  • gRPC/Protobuf: High-performance inter-service communication.
  • Documentation: OpenAPI (Swagger), GraphiQL.

📝 Common Tasks​

1. RESTful Endpoint Design​

Design a RESTful API for a [Resource, e.g., Library Management System]. Define the endpoints for CRUD operations on [Entity, e.g., Books], including route paths, HTTP methods, request bodies, and success/error response examples in JSON.

2. GraphQL Schema Definition​

Create a GraphQL schema for a [Application Type, e.g., Social Network]. Include types for [User, Post, Comment], and define queries for fetching a user's feed with pagination. Also, define a mutation for adding a comment.

3. API Versioning Strategy​

I need to change my API response format for the `/users` endpoint, but I have mobile apps that rely on the old format. Propose a versioning strategy (URI path vs. Header-based) and show how to implement it in [Framework, e.g., Express.js].

4. Performance Optimization​

My `GET /dashboard` endpoint takes 2 seconds to load because it aggregates data from 5 different services. Suggest a strategy to improve this latency (e.g., Caching, BFF pattern, Async processing) and provide a sequence diagram description.

💾 Standard Boilerplates​

REST Controller (Node/Express)​

// GET /api/v1/resources
app.get('/resources', async (req, res, next) => {
  try {
    const { page = 1, limit = 10 } = req.query;
    const items = await Service.findAll({ page, limit });
    res.status(200).json({
      data: items,
      meta: { page, limit, total: items.length }
    });
  } catch (err) {
    next(err);
  }
});

GraphQL Resolver (Apollo Server)​

const resolvers = {
  Query: {
    user: async (_, { id }, { dataSources }) => {
      return dataSources.userAPI.getUser(id);
    },
  },
  User: {
    posts: async (parent, args, { dataSources }) => {
      // Solves N+1 using DataLoader usually found in dataSources
      return dataSources.postAPI.getPostsByUser(parent.id);
    }
  }
};