Practice Problems

Pick a problem by area and get it passing.

Practice problems organized by area. Filter by status to work through not-started, in-progress, or passed problems.

HTTP Basics95

Core judgment on methods, status codes, headers, queries, and bodies.

Read specs and judge whether requests or responses are correct.

Shape the structure, types, and unnecessary fields of requests/responses.

Implement validation, error handling, and response formatting.

Write SELECT, JOIN, aggregation, and update queries.

Identify causes from test results and spot missing test cases.

Distinguish authentication from authorization; handle tokens and cookies.

Handle injection, data leaks, authorization flaws, and other real incidents.

Investigate logs, environment variables, and incidents.

Design decisions for URLs, error formats, pagination, and idempotency.