Crux (formerly Game Server Backend) is a hosted multiplayer backend platform that bundles player auth, persistent data, leaderboards, economy, dedicated server management, live config delivery, and matchmaking behind one API — purpose-built for indie and mid-size studios shipping server-based games.
What is Crux?
Crux is a single-platform backend for multiplayer games. It takes player credentials, game scores, server heartbeats, and config bundles as input, and returns authenticated sessions, stored progression, ranked leaderboards, discoverable server listings, and live runtime settings. The service runs on Supercraft’s infrastructure, using a Go API server backed by PostgreSQL and Redis. The project is open source on GitLab.
Key Features
- Player Authentication — Email/password, guest sessions, OAuth (Google, GitHub, Discord), and Roblox verification. Supports anonymous-to-account upgrades.
- Persistent Player Data — Player-scoped and project-scoped JSON documents with server-authoritative patch semantics for progression, inventory, and shared game state.
- Leaderboards — Ranked and seasonal boards with configurable rules, fast ranking reads, recurring resets, and anti-cheat write guards.
- Economy — Currencies, virtual items, and inventories with atomic updates and full server-side transaction audit.
- Dedicated Server Registry — Register, heartbeat, and search dedicated servers by region; powers server browsers and session discovery.
- Live Config Delivery — Upload versioned config bundles and activate per environment (balance, loot tables, rotations) without a client patch.
- Matchmaking — Tickets, rulesets, region-aware allocation, and admin queue management that wires to your own servers or a reserved pool.
- Social — Friends list, pending requests, and block management — a self-contained social graph.
Who is it for?
- Indie and mid-size studios building dedicated-server games (survival, co-op, PvP) who need backend velocity without hiring a platform team.
- Unity, Roblox, and Godot developers who want drop-in SDKs that wrap the REST API in engine-idiomatic calls (e.g.,
Crux.submit_score("global", id, 9001) in Godot).
- Live-ops engineers who need to push balance changes and seasonal content instantly without client updates.
What can you do with Crux?
- Server-authoritative reward flow: Submit scores from a dedicated server, update player inventory via the economy API, and return atomic transaction results.
- Server browser: Dedicated servers heartbeat their state to the registry; players query by region and see active sessions.
- Seasonal leaderboard rollout: Create a board with a reset schedule, publish new config bundle for loot tables, and let players compete — all from the dashboard.
How does Crux work?
Sign up for a free Dev plan, create a project and environment, then integrate the SDK (Unity, Roblox, Godot, JS) or hit the REST API directly. The platform separates trust boundaries: API keys for admin scripts, server tokens for dedicated game servers, and JWTs for authenticated players. The dashboard provides live observability — player writes, server heartbeats, config pushes — and SDK quickstarts for each engine.
Pricing
Free forever on the Dev plan: up to 2,000 monthly active users and 2 million API calls per month. No credit card required. Paid tiers are available for higher scale — see pricing page.
FAQ
Is Crux free to start?
Yes. The Dev plan is free forever and includes 2,000 MAU and 2M API calls per month. No credit card is needed to sign up.
Which game engines does Crux support?
Crux provides SDKs for Unity, Roblox, Godot, and JavaScript (Node.js/browser). For custom engines, the REST API is fully documented — view API docs.
