Practical Tips for REST API Design Using Richardson’s Maturity Model to Build Consistent, Scalable, and Easy-to-Use APIs

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Designing high-quality REST APIs is both an art and a science. While many teams often focus on delivering functionality quickly, the long-term usability, consistency, and scalability of an API can suffer without a clear architectural strategy. This is where Richardson’s Maturity Model (RMM) becomes a practical guiding framework. It helps designers and developers understand how to evolve an API from simple, ad-hoc implementations to fully RESTful systems that maximize clarity, discoverability, and interoperability.

This article explores practical tips for REST API design using RMM as a foundation. You will find clear explanations, actionable implementation patterns, and multiple code examples to help you build APIs that are easy to use, maintain, and scale.

Understanding Richardson’s Maturity Model

Before jumping into design patterns, it’s essential to understand the structure of RMM. Proposed by Leonard Richardson, the model categorizes REST API maturity into four levels, each representing increasing compliance with REST principles:

  1. Level 0 – The Swamp of POX
    APIs behave like RPC endpoints, often using a single URI and relying heavily on POST.

  2. Level 1 – Resources
    APIs introduce multiple resource-based URIs but may still misuse HTTP methods.

  3. Level 2 – HTTP Verbs and Status Codes
    APIs properly use HTTP methods (GET, POST, PUT, DELETE) and meaningful status codes.

  4. Level 3 – HATEOAS (Hypermedia as the Engine of Application State)
    APIs provide links to next actions, making them discoverable and self-navigable.

Each step of the model adds structure and clarity, reducing ambiguity for consumers and enforceable constraints for servers.

Designing API Resources: Moving From RPC Toward REST

A common starting point for beginners is treating HTTP as a transport layer for remote procedure calls. This often looks like:

POST /getAllUsers
POST /createNewUser
POST /updateUser

While functional, this offers no meaningful mapping between real-world entities and endpoints.

Practical Tips for Resource Modeling

  1. Identify Entities and Collections
    Every core business entity should have a dedicated resource.
    Example entities: users, orders, products.

  2. Use Nouns for Endpoints, Not Verbs
    Replace createOrder with /orders.

  3. Expose Collections and Individual Items

    • /orders — collection

    • /orders/{orderId} — specific resource

  4. Avoid Deeply Nested URIs
    Use nesting only when a real hierarchical relationship exists.
    Example of good nesting:
    /users/{userId}/orders
    Example of excessive nesting:
    /users/{userId}/orders/{orderId}/items/{itemId}/discounts/{discountId}

Level 1 to Level 2: Using HTTP Methods Correctly

The movement from RMM Level 1 to Level 2 is one of the biggest leaps because it harnesses the true power of HTTP.

Common Methods in REST APIs

Method Operation Example
GET Retrieve resource GET /users/1
POST Create resource POST /users
PUT Replace entire resource PUT /users/1
PATCH Modify partial resource PATCH /users/1
DELETE Remove resource DELETE /users/1

A Well-Structured RESTful User Resource

GET a List of Users

GET /users

Response:

[
{ "id": 1, "name": "Jane Doe" },
{ "id": 2, "name": "John Smith" }
]

POST to Create a User

POST /users
Content-Type: application/json{
“name”: “Alice Johnson”,
“email”: “alice@example.com”
}

PUT to Update a User

PUT /users/1
Content-Type: application/json{
“name”: “Jane Doe Updated”,
“email”: “jane_new@example.com”
}

PATCH to Modify a Single Field

PATCH /users/1
Content-Type: application/json{
“email”: “jane_updated@example.com”
}

DELETE to Remove a User

DELETE /users/1

Correct usage of verbs improves consistency and readability and contributes directly to making APIs self-explanatory.

Designing Meaningful and Consistent HTTP Status Codes

REST APIs should leverage the semantics of HTTP status codes to communicate clearly with clients.

Common Status Codes You Should Use

  • 200 OK — Successful GET, PUT, PATCH, DELETE

  • 201 Created — Successful POST

  • 204 No Content — Successful DELETE or update without response body

  • 400 Bad Request — Invalid input

  • 401 Unauthorized — Authentication required

  • 403 Forbidden — No permission

  • 404 Not Found — Resource doesn’t exist

  • 409 Conflict — Resource state conflict

  • 500 Internal Server Error — Unexpected failure

Error Response Structure

{
"error": "ValidationError",
"message": "Email address is required",
"details": {
"field": "email"
}
}

Tip: Keep your error format consistent across every endpoint.

Implementing HATEOAS (Level 3): Making APIs Self-Describing

Reaching Level 3 of RMM involves linking your endpoints together to guide clients toward available actions.

HATEOAS in Action

{
"id": 7,
"name": "Jane Doe",
"links": [
{ "rel": "self", "method": "GET", "href": "/users/7" },
{ "rel": "update", "method": "PUT", "href": "/users/7" },
{ "rel": "orders", "method": "GET", "href": "/users/7/orders" }
]
}

Benefits of HATEOAS:

  • Clients discover actions dynamically

  • Fewer hardcoded routes in client applications

  • Smoother evolution of APIs over time

Although not universally adopted, HATEOAS is powerful in large, evolving distributed systems.

Practical Naming and Versioning Strategies

Use Consistent Naming Conventions

  • Use lowercase, plural nouns: /users, /orders

  • Avoid special characters: /products, not /prdcts-list

  • Keep URIs simple: /users/1/preferences

API Versioning Options

  1. URI Versioning
    /v1/users

    • Explicit and simple

    • Most common in production systems

  2. Header Versioning
    Accept: application/vnd.company.v2+json

    • Cleaner URLs but harder debugging

  3. Query Param Versioning
    /users?version=2

    • Usually discouraged as it mixes concerns

Choose one strategy and apply it consistently.

Pagination, Filtering, and Sorting for Scalable APIs

As datasets grow, returning thousands of records becomes expensive. Pagination helps manage this.

Pagination Query Parameters

GET /users?page=2&limit=20

Example Response

{
"data": [ /* 20 users here */ ],
"pagination": {
"page": 2,
"limit": 20,
"totalPages": 10,
"totalRecords": 200
}
}

Filtering Example

GET /users?role=admin&isActive=true

Sorting Example

GET /products?sort=price&order=asc

Design tip: Use predictable parameter names across all endpoints.

Designing Request and Response Payloads

Principles for Clean Data Structures

  1. Don’t leak internal database fields like _id or mongoVersion.

  2. Use camelCase or snake_case consistently (camelCase is common in REST JSON).

  3. Remove unnecessary wrappers, e.g.,
    Avoid: { "data": { "user": { … } } }
    Prefer: { "id": 7, "name": "Alice" }

Good Request Payload

{
"name": "Travel Backpack",
"description": "Lightweight carry-on bag",
"price": 89.99,
"inStock": true
}

Good Response Payload

{
"id": 122,
"name": "Travel Backpack",
"price": 89.99,
"links": [
{ "rel": "self", "href": "/products/122" }
]
}

Security Best Practices You Should Always Implement

Use HTTPS Everywhere

Plain HTTP is no longer acceptable for API traffic.

Prefer Standard Authentication Schemes

  • OAuth 2.0

  • JWT-based tokens

  • API keys as a last resort for server-to-server traffic

Validate All Inputs

Never trust client input. Use strict schema validators.

Avoid Over-Exposing Data

Implement field-level whitelists or projections.

Rate Limiting and Throttling

Protect your API from abuse and unpredictable load.

Implementing Consistency Through API Contracts

Use OpenAPI (Swagger) Standards

Writing OpenAPI specs ensures:

  • Predictable structure

  • Self-documenting APIs

  • Easier client SDK generation

  • Cross-team clarity

Example Snippet

paths:
/users:
get:
summary: Get all users
responses:
'200':
description: A list of users

The spec becomes a source of truth for future developers.

Handling Partial Updates Gracefully With PATCH

PATCH is often overlooked but highly valuable for reducing bandwidth and improving performance.

PATCH Request

PATCH /users/1
Content-Type: application/json{
“phoneNumber”: “+1-202-555-0123”
}

Avoid requiring full objects for minor changes.

Supporting Bulk Operations for Large Systems

Bulk endpoints reduce repetitive network calls.

Bulk Insert

POST /products/bulk
Content-Type: application/json[
{ “name”: “Item A”, “price”: 12 },
{ “name”: “Item B”, “price”: 25 }
]

Bulk Delete

DELETE /users/bulk
Content-Type: application/json{
“ids”: [ 32, 45, 78 ]
}

Bulk operations improve throughput and simplify client logic.

Ensuring Backward Compatibility as APIs Evolve

The best APIs evolve without breaking older clients.

Strategies:

  • Support deprecated fields for at least one version cycle

  • Add new functionality without modifying existing behavior

  • Use versioning for breaking changes

  • Provide deprecation warnings in responses

Backward compatibility preserves trust among API consumers.

Conclusion

Building REST APIs that truly excel—those that developers enjoy using and businesses can scale indefinitely—requires deliberate design decisions. Richardson’s Maturity Model offers a clear, incremental roadmap for improving API quality: start with identifying resources, adopt proper HTTP methods, implement meaningful status codes, and optionally advance into hypermedia-driven interactions.

By applying practical techniques such as consistent naming, predictable versioning, useful pagination, proper request/response design, security best practices, and backward-compatible evolution, you create APIs that stand the test of time. These are not merely technical endpoints—they become reliable, intuitive products in themselves.

In a world increasingly powered by distributed systems and microservices, a well-designed REST API becomes a foundational asset. Whether you are building internal services, third-party developer products, or customer-facing integrations, your API sets the tone for usability, maintainability, and performance. Thoughtful REST design leads to fewer surprises for consumers, smoother scaling for engineering teams, and a more robust overall system architecture.

By aligning your approach with the principles discussed here—and continuously iterating as your system grows—you can deliver consistent, scalable, and easy-to-use APIs that reflect modern best practices and embody the full power of REST.