Crux is a backend platform designed for multiplayer games, primarily aimed at developers using Unity, Godot, Roblox, and custom game servers. It aims to replace scattered tools for authentication, player storage, leaderboard logic, server discovery, and runtime configuration by providing backend capabilities through a unified API.
Main Capabilities
- Player Authentication: Supports email and password, guest sessions, OAuth (Google, GitHub, Discord), and Roblox verification, helping implement real accounts, onboarding flows, and player access control.
- Persistent Data: Provides player-level and project-level JSON documents for progress, profiles, unlocks, event flags, inventory, and shared runtime values, with server authority and patch semantics.
- Leaderboards: Supports ranked and seasonal boards, with configurable rules, fast rank reads, periodic resets, and support for limited-time events or score-based cycles, with anti-cheat mechanisms on writes.
- Economy System: Manages currencies, virtual items, and inventory, with atomic server-authoritative updates for rewards, spending, and grants.
- Server Registration: Registers, heartbeats, and searches dedicated servers, supporting server browsers, active session discovery, region-aware listings, and stale cleanup.
- Live Configuration: Uploads versioned configuration bundles and activates them per environment, allowing balance adjustments, rotations, loot tables, and rule sets to take effect without a full patch.
- Matchmaking: Queues by game mode and region, polls match results, and returns the active server where the match is located (from its own registry, avoiding crashed servers as targets). Queues can be managed from the dashboard, including manual party formation.
- Social Graph: Provides friends, pending requests, and blocking, letting players connect without a third-party identity provider.
- Stats and Achievements: The backend owns named counters that can be queried for progress; achievements are bound to stats and thresholds, unlocked in the same transaction as the write, and responses return earned achievements only once, preventing duplicate rewards.
Usage
Developers can integrate through the public HTTP API and OpenAPI contract. Client SDKs (JavaScript, Godot, Unity, Roblox) are open source on GitHub under the MIT License. The hosted backend itself is a proprietary hosted service. For scenarios requiring authoritative servers, Crux Runtime allows uploading a Godot 4 Linux dedicated server export package, obtaining an isolated European authoritative process, READY endpoint, and short-termjoin tickets, logs, trusted results, and clean termination. Runtime is currently a capacity-limited closed Alpha, and accepted Dev projects receive limited evaluation credits.
Suitable Scenarios
- Dedicated server games
- Multiplayer survival and co-op games
- Region-based game server clusters
- Unity, Roblox, Godot, and custom engine backends
- Indie and mid-sized studios that want backend capabilities quickly and avoid building a platform team before shipping gameplay
Limitations and Non-Applicable Cases
- Purely offline, single-player games
- Projects that only need a general-purpose login database
- Projects that need a highly specialized AAA matchmaking stack from day one
- Runtime compute is not an unlimited free feature and is currently capacity-limited
Free and Open Source Information
The Dev BaaS plan is free forever, including 10,000 MAU, unlimited projects, and all BaaS features. Runtime is billed separately and is currently capacity-limited; accepted Dev projects receive three lifetime evaluation hours, one concurrent session, and a one-hour session limit. Client SDKs are open source on GitHub under the MIT License, and the hosted API contract is published as OpenAPI. All players, documents, leaderboards, and configurations can be exported through the same API, with a commitment to data portability. If the service is terminated, there are written advance notice and export window commitments.
