Kahoots API

An HTTP API for running Kahoot-style quiz games: a host builds a quiz, players join a live session with a game code, and everyone answers the same timed multiple-choice questions. Built with TypeScript, Express, and Node, with quizzes and game state persisted in MongoDB.

The API is organized around three resources exposed over HTTP. A quiz is an ordered list of questions, each with its choices and the index of the correct one. A game is a session created from a quiz, identified by a join code. A player belongs to a game and accumulates a running score. Express routers expose create, read, update, and delete over each, and Mongo stores them as documents so a session survives between requests rather than living in process memory.

Scoring is time-weighted: a correct answer earns points scaled by how quickly it arrives inside the question's time limit, and a wrong answer earns nothing. With response time $t$ and question limit $T$, the standard rule awards

for a correct answer and $0$ otherwise, so an instant answer is worth the full $P_{\max }$ and one at the buzzer is worth half. The server times each question from when it is served, which keeps scoring authoritative on the backend rather than trusting a client-reported clock.

The game flow runs as a small state machine: a session moves through a lobby while players join, then one question phase per question, then a results phase that reveals the answer and the updated standings. The server holds the current phase and advances it, so every client reads the same state from one source.