Discord

Discord's API is comprehensive and developer-friendly, offering REST and WebSocket protocols for real-time communication.

OAuth2 and bot token authentication are straightforward with excellent documentation and OpenAPI specs on GitHub. The API covers guilds, channels, messages, voice, webhooks, and slash commands extensively. Rate limits are reasonable (50/s global, customizable to 1200/s), with strong community library support across multiple languages. However, bot verification is required for servers over 100, and some endpoints require specific intents. The API excels at building community bots, custom integrations, and automation tools.

It's ideal for gaming communities, content creators, and businesses needing real-time communication features, with completely free access for most use cases.