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Manu Kumar Pal
Manu Kumar Pal

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API Design Basics Every Backend Developer Should Know

#backend #api #rest #webdev

APIs are contracts.
If the contract is unclear, things break — slowly or suddenly.

This API design covers basics that make your APIs easier to use, safer to change, and harder to break.

1️⃣ Use HTTP Status Codes Properly

Status codes are not optional metadata — they’re signals.

❌ Bad

200 OK
{
  "error": "User not found"
}
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✅ Good

404 Not Found
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Common codes to remember:

200 → success

201 → created

400 → bad request

401 → unauthorized

403 → forbidden

404 → not found

500 → server error

2️⃣ Keep URLs Simple and Clear

URLs should describe resources, not actions.

❌ Bad

/getUser
/createOrder
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✅ Good

GET /users/{id}
POST /orders
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Let HTTP methods do the work.

3️⃣ Be Consistent With Responses

Inconsistent responses confuse clients.

❌ Bad

{ "msg": "ok" }

{ "success": true }
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✅ Good

{
  "data": {...},
  "meta": {...}
}
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Consistency makes APIs predictable.

4️⃣ Design Errors Like a Feature

Errors should be helpful, not mysterious.

❌ Bad

{ "error": "Something went wrong" }
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✅ Good

{
  "error": {
    "code": "INVALID_INPUT",
    "message": "Email format is invalid"
  }
}
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Clear errors reduce support and debugging time.

5️⃣ Always Paginate Lists

Large responses hurt performance.

❌ Bad

GET /users
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✅ Good

GET /users?page=1&limit=20
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Response:


{
  "data": [...],
  "page": 1,
  "limit": 20,
  "total": 250
}
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Pagination protects your API and database.

6️⃣ Version Your API Early

Breaking changes happen — plan for them.

✅ Good

/api/v1/users
/api/v2/users
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Versioning lets clients upgrade safely.

7️⃣ Don’t Overload One Endpoint

One endpoint should do one thing well.

❌ Bad

POST /users?action=createAndSendEmailAndLog
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✅ Good

POST /users
POST /emails
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Simple endpoints are easier to test and maintain.

8️⃣ Secure by Default

Never assume clients behave correctly.

Basics to follow:

➡️ Validate inputs

➡️ Authenticate every request

➡️ Authorize every action

➡️ Rate limit public endpoints

Security is part of API design, not an add-on.

9️⃣ Document Everything

APIs without docs slow everyone down.

Use tools like:

➡️ OpenAPI / Swagger

Docs are part of your API.

🎯 Final Thoughts

Good API design is not about being clever.
It’s about being clear, predictable, and boring.

And that’s a good thing.

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