p99 ships one production incident a day. Every case is something that genuinely happened in a real system, and every fix is one that has genuinely worked — no puzzles with hidden tricks.
Each incident is presented the way it actually unfolds: a symptom, the constraints that narrow it down, the evidence gathered so far, and then the question. The diagnosis stays locked until you ask for it, because the part worth practising is the part before the answer.
The site covers caching, databases, runtime and platform incidents, with an archive, topic filtering, a reading streak, and a newsletter for the daily send.