HTTP Status Codes
| Code | Meaning | Typical Scenarios |
|---|---|---|
| 200 | Success | Request processed |
| 400 | Bad Request | Invalid parameters |
| 401 | Unauthorized | Invalid authentication |
| 403 | Forbidden | Insufficient permissions |
| 404 | Not Found | Resource doesn't exist |
| 409 | Conflict | Duplicate request |
| 422 | Unprocessable | Business rule violation |
| 429 | Too Many Requests | Rate limit exceeded |
| 500 | Server Error | Internal server issue |
| 502 | Bad Gateway | Upstream service error |
| 503 | Service Unavailable | Maintenance/downtime |