Choosing the Right HTTP Status Code in REST APIs (A Practical Guide)

Source: Dev.to

Choosing the correct HTTP status code in REST APIs sounds simple — until you work on real projects.
In practice, the same issues keep appearing:

• 200 OK returned for validation errors
• Confusion between 400 and 422
• 401 and 403 used interchangeably
• Business‑rule failures mapped to random 4xx codes

These small inconsistencies slowly break API contracts and make frontend–backend collaboration harder.

Live Demo

https://ramkumar-kollimalayan.github.io/rest-api-response-code-helper/

GitHub Repository

https://github.com/ramkumar-kollimalayan/rest-api-response-code-helper

Status Code Comparisons

400 vs 422

• 400 Bad Request – The request is malformed or structurally invalid.
• 422 Unprocessable Entity – The request is syntactically correct, but business validation failed.
  Use 422 when the payload is correct but domain rules are violated.

401 vs 403

• 401 Unauthorized – Authentication is missing or invalid.
• 403 Forbidden – The user is authenticated but does not have permission.
  This distinction becomes very important when building secure APIs.

409 Conflict

Typical scenarios:

• Duplicate data
• Version conflicts
• Business rule violations

Visual Helper

After repeatedly explaining these choices in code reviews, I built a small visual helper that maps common REST API scenarios to appropriate HTTP status codes.

Goals

• Simplicity over completeness
• REST‑focused usage (not browser behavior)
• Clear “when to use” guidance
• Real‑world API scenarios

Observations

What surprised me most was how often developers treated this as a reference rather than a one‑time read. It reinforced the idea that small, focused tools solving everyday confusion can be more useful than large, exhaustive documentation.

Call for Feedback

If you design or review APIs regularly, I’d love to hear:

• Which HTTP status codes you see misused most
• Any scenarios where you would choose differently

Thanks for reading!