APIs Beginner
HTTP Status Defender
Choose the correct HTTP status code for realistic backend scenarios and learn the response semantics behind each answer.
- Time
- 5-8 minutes
- Concept
- HTTP status codes and response semantics
Backend concept
HTTP Semantics
Status codes, methods, caching headers, and response meaning for backend APIs.
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Why this matters
Clear HTTP semantics help clients retry, cache, authenticate, and recover correctly.
How to practice
Review when to use success, redirect, client error, and server error responses.
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Learning objectives
- Map common API outcomes to precise HTTP status codes.
- Distinguish authentication, authorization, validation, and conflict responses.
- Recognize when success responses should include a body, a location, or no content.
- Explain when browsers send CORS preflight requests.
- Choose safe Access-Control headers for origins, credentials, methods, and headers.
- Avoid common CORS mistakes such as wildcard credentials and unsafe origin reflection.
Common mistakes to avoid
- Returning 200 OK for every API response and hiding errors inside the JSON body.
- Using 404 Not Found for authorization failures that should be 403 Forbidden.
- Using 500 Internal Server Error for client validation mistakes.
- Reflecting any Origin header for sensitive authenticated APIs.
- Combining wildcard origins with credentials.
- Forgetting Vary: Origin when CORS responses differ by origin.
Games for HTTP Semantics
Start with the first game, then use local review history to revisit missed decisions.
APIs Intermediate
CORS Preflight Pilot
Guide browser API requests through CORS decisions covering origins, preflight, credentials, exposed headers, and cache safety.
- Time
- 6-9 minutes
- Concept
- CORS, browser security boundaries, and preflight response design
APIs Beginner
API Route Builder
Design REST-style methods and routes for product requirements such as creating users, updating email, searching products, and nested comments.
- Time
- 6-9 minutes
- Concept
- REST API route design