Skill Challenges
3-minute drills that sharpen the developer skills you actually use.
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Skill of the day
All challenges
- Regex Rescue — Build or choose the right regex to match valid strings and reject invalid ones.
- API Detective — Find the bug in an API request/response: status codes, headers, JWT, CORS, and more.
- Payload Patch — Pick the right transformation to fix a broken JSON payload.
- JSONPath Quest — Pick the JSONPath expression that returns the target output.
- Diff Detective — Spot the meaningful change between two snippets that may break consumers.
- JWT Heist — Identify what's wrong with a JWT — alg=none, expired, aud mismatch, RS↔HS confusion, and more.
- Cron TimeLock — Pick the cron that matches the intent, or spot the bug in the given cron.
- CSV Sleuth — Find the missing or duplicated row between two CSV snapshots.
- Dockerfile Watch — Pick the dangerous or non-reproducible line in a Dockerfile snippet.
- SQL Join Maze — Pick the SQL join that produces the target result set.
- Secret Hunter — Spot the leaked secret in a config or code snippet.
- Signature Forensics — Pick the reason this webhook signature verification failed.