Application Programming Interfaces (APIs) form the backbone of modern software ecosystems, enabling seamless communication between applications, services, and devices.
89% of developers say APIs are essential to their organizations’ operations. Yet, poor API design can lead to integration failures, increased development time, and negative developer experience. Following proven API best practices ensures that APIs are not only functional but also intuitive, secure, and maintainable over time.
Characteristics of a Well-Designed API
A well-designed API shares certain core traits that make it reliable and easy to adopt:
- Easy to read and work with: Resource names, endpoints, and methods are logically structured so developers can quickly understand how to interact with the API.
- Hard to misuse: Clear feedback, intuitive error messages, and a predictable structure prevent accidental misuse.
- Complete yet concise: All necessary functionality is available without overloading developers with unnecessary complexity. The design evolves with use cases while maintaining clarity.
Read More: What is API Testing? (with Examples)
Why Follow API Best Practices?
The benefits of adhering to established API best practices extend beyond clean code:
- Improved developer adoption — A straightforward API attracts more developers to integrate it into their workflows.
- Reduced integration errors — Standardization and predictability reduce the risk of incorrect API usage.
- Faster time to market — Well-documented and logically designed APIs accelerate onboarding.
- Easier maintenance and scaling — Consistency across endpoints simplifies future updates and expansions.
Top API Best Practices to Follow
Here are the top API bets practices to follow:
1. Use Clear, Consistent Naming Conventions
Choose resource names that are intuitive, self-explanatory, and consistent across all endpoints.
Example:
- Good: /customers
- Bad: /custData
Sample request:
bash
GET /customers
Sample response:
json
{
"data": [
{ "id": 1, "name": "Alice Johnson" },
{ "id": 2, "name": "David Lee" }
]
}2. Keep URLs Simple and Noun-Based
Avoid verbs in URLs, use plural nouns for collections, and maintain predictable hierarchy.
Example:
- Good: /orders/45/items
- Bad: /fetchOrderItems?id=45
Sample request:
bash
GET /orders/45/items
Sample response:
json
{
"orderId": 45,
"items": [
{ "productId": "A100", "quantity": 2 },
{ "productId": "B200", "quantity": 1 }
]
}3. Align HTTP Methods with CRUD Operations
Use HTTP verbs as intended to clearly convey the action.
Example:
- GET /products → Fetch products
- POST /products → Add a product
Sample POST request:
bash
POST /products Content-Type: application/json
json
{
"name": "Gaming Keyboard",
"price": 79.99
}Sample response:
json
{
"id": 210,
"name": "Gaming Keyboard",
"price": 79.99
}4. Implement Consistent and Informative Responses
Return structured JSON with clear keys and messages.
Sample request:
bash
GET /products/999
Sample error response:
json
{
"error": {
"code": 404,
"message": "Product not found"
}
}5. Validate All Requests
Reject malformed or unsafe inputs before processing.
Sample request:
bash
POST /users Content-Type: application/json
json
{
"email": "not-an-email",
"password": "123"
}Sample response:
json
{
"error": {
"code": 400,
"message": "Invalid email format and weak password"
}
}
6. Handle Errors Gracefully
Always include a clear message, error code, and optional documentation link.
Sample error response:
json
{
"error": {
"code": 403,
"message": "Access denied. Please check your API key.",
"docs": "https://api.example.com/docs/auth"
}
}Read More: What Is API Automation Testing?
7. Use Pagination and Filtering for Large Data Sets
Prevent performance bottlenecks by limiting records and offering filters.
Sample request:
bash
GET /products?category=electronics&limit=5&page=2
Sample response:
json
{
"page": 2,
"limit": 5,
"total": 47,
"data": [
{ "id": 12, "name": "Smartphone", "price": 699 },
{ "id": 14, "name": "Tablet", "price": 299 }
]
}8. Secure Your API with Authentication and Encryption
Require secure protocols and valid credentials.
Sample request with bearer token:
sql
GET /account Authorization: Bearer eyJhbGciOiJIUzI1NiIsInR5cCI6IkpXVCJ9...
Sample response:
json
{
"id": 101,
"name": "John Smith",
"membership": "Premium"
}9. Optimize Performance with Caching and Compression
Use caching headers and payload compression.
Sample response with caching:
arduino
Cache-Control: public, max-age=3600 ETag: "f3b12a7"
json
{
"id": 12,
"name": "Laptop",
"price": 1299
}Read More: Top 20 API Testing Tools
10. Version Your API for Long-Term Stability
Clearly label versions to prevent breaking changes.
Example:
- /v1/users
- /v2/users
Sample request:
bash
GET /v2/users/15
Sample response:
json
{
"id": 15,
"name": "Sophia Brown",
"email": "sophia@example.com"
}In RESTful API design, resources are the central elements that represent entities such as users, products, or orders. A collection is a group of similar resources — for example, /users represents all user records, while /orders represents all order records. Each resource within a collection is uniquely identified via a URL.
Best practices for structuring URLs:
Use nouns, not verbs
Endpoints should describe what the resource is, not what it does. The HTTP method already communicates the action.
- Good: /users
- Bad: /getUsers
Example:
bash
GET /users
json
{
"data": [
{ "id": 1, "name": "Alice Johnson" },
{ "id": 2, "name": "David Lee" }
]
}Keep collections plural for consistency
Plural nouns make it clear that an endpoint refers to multiple resources.
- /photos for all images
- /orders for all orders
Maintain a logical hierarchy
Use nested paths to represent relationships between entities.
bash
GET /users/7/orders
json
{
"userId": 7,
"orders": [
{ "orderId": 101, "status": "delivered" },
{ "orderId": 102, "status": "pending" }
]
}Keep URLs clean and readable
Use lowercase letters and hyphens for clarity, avoid special characters.
- Good: /product-categories
- Bad: /prdCat
Describing Resource Functionality with HTTP Methods
HTTP methods define the type of action that can be performed on a resource. Correct mapping ensures predictable behavior.
GET — Retrieve a resource without altering it.
bash
GET /products/123
json
{
"id": 123,
"name": "Wireless Mouse",
"price": 29.99
}POST — Create a new resource.
bash
POST /products Content-Type: application/json
json
{
"name": "Mechanical Keyboard",
"price": 79.99
}Response:
json
{
"id": 210,
"name": "Mechanical Keyboard",
"price": 79.99
}PUT — Fully replace an existing resource.
bash
PUT /users/15 Content-Type: application/json
json
{
"name": "Sophia Brown",
"email": "sophia@example.com"
}PATCH — Update part of a resource.
bash
PATCH /users/15 Content-Type: application/json
json
{
"email": "newemail@example.com"
}DELETE — Remove a resource.
bash
DELETE /orders/45
json
{
"message": "Order 45 deleted successfully"
}Responses
Clear, consistent responses make it easy for developers to understand the result of their request.
Best practices for responses:
- Use standard HTTP status codes
- 200 OK — Successful retrieval
- 201 Created — Resource created
- 400 Bad Request — Client-side error
- 404 Not Found — Resource missing
- 500 Internal Server Error — Server failure
Provide clear, self-descriptive error messages
bash
GET /products/999
json
{
"error": {
"code": 404,
"message": "Product not found"
}
}Return consistent formats
Stick to a single format (e.g., JSON) across all endpoints.
Include example responses in documentation
bash
GET /products
json
{
"data": [
{ "id": 101, "name": "Laptop", "price": 1299 },
{ "id": 102, "name": "Smartphone", "price": 699 }
]
}Requests
API requests should allow flexibility for developers to retrieve exactly what they need without unnecessary complexity.
Best practices for handling requests:
Use query parameters for filtering and sorting
bash
GET /products?category=electronics&sort=price_desc&limit=5
json
{
"page": 1,
"limit": 5,
"data": [
{ "id": 12, "name": "Smartphone", "price": 699 },
{ "id": 14, "name": "Tablet", "price": 299 }
]
}Use path parameters for specific resources
bash
GET /users/987
json
{
"id": 987,
"name": "Michael Carter",
"joined": "2021-03-15"
}Implement pagination for large datasets
bash
GET /orders?page=3&limit=20
json
{
"page": 3,
"limit": 20,
"total": 180,
"data": [ /* order objects */ ]
}Validate request inputs
json
{
"error": {
"code": 400,
"message": "Missing required parameter: category"
}
}Security and Performance Considerations
An API must remain secure to protect data and performant to ensure smooth operation under load.
Best practices:
- Enforce HTTPS/TLS to protect data in transit.
Implement authentication and authorization
sql
GET /account Authorization: Bearer eyJhbGciOiJIUzI1...
json
{
"id": 101,
"name": "John Smith",
"membership": "Premium"
}Apply rate limiting to prevent abuse.
makefile
X-RateLimit-Limit: 100 X-RateLimit-Remaining: 75
- Validate and sanitize inputs to block malicious requests.
Use caching and compression to improve speed.
arduino
Cache-Control: public, max-age=3600 ETag: "a1b2c3"
Continuous Improvement and Versioning
APIs evolve over time, and careful versioning prevents disruption to existing integrations.
Best practices:
Use semantic versioning in URLs or headers.
bash
GET /v2/users/15
json
{
"id": 15,
"name": "Sophia Brown",
"email": "sophia@example.com"
}- Avoid breaking changes unless in a new version.
- Communicate deprecations with clear timelines.
- Gather feedback from API consumers to guide improvements.
Requestly for API Testing
Requestly makes API testing faster and more flexible by letting developers intercept, modify, and mock requests without changing backend code.
Its API Client provides a clean interface to send requests, inspect responses, and organize collections for ongoing testing — similar to Postman, but integrated with Requestly’s powerful interception rules. This combination allows teams to mock endpoints before the backend is ready, test edge cases, switch environments instantly, and debug API traffic in real time.
Conclusion
Following API best practices transforms an API from a functional interface into a valuable, developer-friendly product. By focusing on clear structure, consistent behavior, strong security, and continuous improvement, organizations can deliver APIs that are scalable, secure, and easy to integrate. Combining these with effective testing tools like Requestly ensures APIs meet high reliability and performance standards before release.
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