# Crowded Kingdoms APIs

> Crowded Kingdoms is a platform for massive multiplayer worlds. There are three public APIs: the Management API (identity, organizations, apps marketplace, access tiers, billing, payments, quotas, environments — GraphQL), the Game API (runtime world/replication data and the realtime UDP-proxy subscription stream — GraphQL), and the Replication API / "Buddy" (a binary UDP wire protocol for low-latency spatial replication). Browser clients should use the CrowdyJS TypeScript SDK. All GraphQL calls use an `Authorization: Bearer <token>` header; the token comes from a Management API `login`/`register`. BigInt values are decimal strings; timestamps are ISO-8601 UTC.

## Start here (for AI agents and integrators)

- [For AI agents — quickstart & end-to-end workflows](https://docs.crowdedkingdoms.com/overview/for-ai-agents): get a dev-tier key, the SDL/introspection URLs, and the most common flows (register → token → host discovery → spatial send; and the studio-backend economy flow).
- [Overview / client workflow](https://docs.crowdedkingdoms.com/overview/client-workflow): the two-endpoint model (Management API + Game API).
- [Discord community support](https://discord.gg/x7tMKGwHf): ask questions and get help from the Crowded Kingdoms community.

## Schema (downloadable SDL)

- [Management API SDL](https://docs.crowdedkingdoms.com/schema/management-api.graphql)
- [Game API SDL](https://docs.crowdedkingdoms.com/schema/game-api.graphql)
- [CrowdyJS SDL](https://docs.crowdedkingdoms.com/schema/crowdyjs.graphql)
- Introspection is enabled on the dev tier; the GraphQL Playground is served at each API's `/graphql` endpoint.

## Conventions (read before calling)

- [Error codes (GraphQL extensions.code + UDP UdpErrorCode) with remediation](https://docs.crowdedkingdoms.com/overview/error-codes)
- [Pagination conventions](https://docs.crowdedkingdoms.com/overview/pagination)
- [Rate limits and query cost](https://docs.crowdedkingdoms.com/overview/rate-limits)
- [Authentication (Game API: bearer token + ws connection_init)](https://docs.crowdedkingdoms.com/game-api/authentication)

## Management API (GraphQL — identity, apps, billing)

- [Management API intro](https://docs.crowdedkingdoms.com/management-api/intro)
- [Management API guide](https://docs.crowdedkingdoms.com/management-api/readme)
- [GraphQL reference (operations & types)](https://docs.crowdedkingdoms.com/management-api/reference/graphql-overview)
- [Dedicated environments](https://docs.crowdedkingdoms.com/management-api/dedicated-environments) · [Shared environment](https://docs.crowdedkingdoms.com/management-api/shared-environment) · [Game setup](https://docs.crowdedkingdoms.com/management-api/game-setup)

## Game API (GraphQL — world data + realtime UDP proxy)

- [Game API intro](https://docs.crowdedkingdoms.com/game-api/intro)
- [Authentication](https://docs.crowdedkingdoms.com/game-api/authentication)
- [GraphQL UDP-proxy API (subscriptions + spatial sends)](https://docs.crowdedkingdoms.com/game-api/graphql-udp-proxy-api)
- [Host discovery](https://docs.crowdedkingdoms.com/game-api/host-discovery) · [Permissions](https://docs.crowdedkingdoms.com/game-api/permissions) · [Grids & permissions](https://docs.crowdedkingdoms.com/game-api/grids-and-permissions)
- [Teams](https://docs.crowdedkingdoms.com/game-api/teams) · [Channels](https://docs.crowdedkingdoms.com/game-api/channels) · [Avatar state](https://docs.crowdedkingdoms.com/game-api/avatar-state) · [Actor state](https://docs.crowdedkingdoms.com/game-api/actor-state)
- [Game models](https://docs.crowdedkingdoms.com/game-api/game-models) · [Autonomous processes (NPCs)](https://docs.crowdedkingdoms.com/game-api/autonomous-processes) · [Model-driven notifications](https://docs.crowdedkingdoms.com/game-api/model-driven-notifications)
- [Choosing Game APIs (five-tier decision flow + mechanic/genre mappings)](https://docs.crowdedkingdoms.com/game-api/model-vs-compute) · [Compute Modules (server-side Rust/WebAssembly logic)](https://docs.crowdedkingdoms.com/game-api/compute-modules) · [Compute host API reference](https://docs.crowdedkingdoms.com/game-api/compute-host-api) · [Compute tutorial (zero to a live module)](https://docs.crowdedkingdoms.com/game-api/compute-tutorial) · [Compute engines (the full template registry: NPC/mob/world/match/deck/instance/director/matchmaking/market/board/minigame/abilities/movement-warden/territory/racing/possession/liveops — deployable by name via computeDeployTemplate)](https://docs.crowdedkingdoms.com/game-api/compute-engines)
- [Modeling game concepts (inventory, object permissions, NPCs)](https://docs.crowdedkingdoms.com/game-api/modeling-game-concepts)
- [GraphQL reference (operations & types)](https://docs.crowdedkingdoms.com/game-api/reference/graphql-overview)

## Replication API / Buddy (binary UDP wire protocol)

- [Replication API intro](https://docs.crowdedkingdoms.com/replication-api/intro)
- [Getting started](https://docs.crowdedkingdoms.com/replication-api/getting-started)
- [Authenticate and assign a server](https://docs.crowdedkingdoms.com/replication-api/authenticate-and-assign)
- [Wire formats (opcodes, long-spatial layout, payloads)](https://docs.crowdedkingdoms.com/replication-api/wire-formats)
- [Send and receive](https://docs.crowdedkingdoms.com/replication-api/send-and-receive)
- [HMAC](https://docs.crowdedkingdoms.com/replication-api/hmac)
- [Operations & error codes](https://docs.crowdedkingdoms.com/replication-api/operations)
- [Troubleshooting](https://docs.crowdedkingdoms.com/replication-api/troubleshooting)
- [Load testing (open-source cks-loadtest tool + game setup)](https://docs.crowdedkingdoms.com/replication-api/load-testing)

## SDKs

- [CrowdyJS (browser-first TypeScript SDK) overview](https://docs.crowdedkingdoms.com/crowdyjs/readme)
- CrowdyJS guides: [Channels](https://docs.crowdedkingdoms.com/crowdyjs/channels) · [Teams](https://docs.crowdedkingdoms.com/crowdyjs/teams) · [Grids](https://docs.crowdedkingdoms.com/crowdyjs/grids) · [Game model](https://docs.crowdedkingdoms.com/crowdyjs/game-model) · [Automations (NPCs)](https://docs.crowdedkingdoms.com/crowdyjs/automations) · [Model-driven notifications](https://docs.crowdedkingdoms.com/crowdyjs/model-notifications) · [Game Kit (inventory, object permissions, NPCs, genre layers)](https://docs.crowdedkingdoms.com/crowdyjs/game-kit) · [World Stores (SDK-managed actor/chunk/message state)](https://docs.crowdedkingdoms.com/crowdyjs/stores)
- [CrowdyCPP (portable C++ SDK with native UDP replication) overview](https://docs.crowdedkingdoms.com/crowdycpp/intro)
- CrowdyCPP guides: [Installation](https://docs.crowdedkingdoms.com/crowdycpp/installation) · [Quick start](https://docs.crowdedkingdoms.com/crowdycpp/quick-start) · [Replication client (native UDP)](https://docs.crowdedkingdoms.com/crowdycpp/replication-client) · [World session (SDK-managed game state)](https://docs.crowdedkingdoms.com/crowdycpp/world-session) · [Game Kit](https://docs.crowdedkingdoms.com/crowdycpp/game-kit) · [Engine integration (Unreal, Godot, Unity)](https://docs.crowdedkingdoms.com/crowdycpp/engine-integration) · [Compatibility & parity](https://docs.crowdedkingdoms.com/crowdycpp/compatibility)
- [Build a game (tutorial)](https://docs.crowdedkingdoms.com/build-a-game/intro)
- [Unreal SDK](https://docs.crowdedkingdoms.com/unreal-sdk/intro)

## Changelog

- [Releases & changelog](https://docs.crowdedkingdoms.com/releases/intro)