Does Crux replace Steamworks?

No. Keep Steamworks for Steam-native identity tickets, lobbies, SDR networking, Steam Cloud, Inventory and Wallet flows where they fit. Crux adds a game-owned backend beside Steamworks for verified Steam-to-player identity, structured persistent data, leaderboards, live config and trusted server operations.

How does Steam login work in Crux?

Your Steam client creates a GetAuthTicketForWebApi ticket using the configured identity string and sends the ticket bytes as hex with the normal publishable Crux key. Crux verifies the ticket with Valve using the project publisher Web API key stored server-side, then maps the verified SteamID64 to a stable Crux player.

Should the Steam publisher Web API key be included in the game build?

No. The publisher Web API key is a trusted server credential. Crux stores it write-only in project configuration and never returns it to the player build.

Steamworks · verified player identity · persistent backend

Keep Steamworks. Give your Steam player a game-owned backend identity.

Crux verifies GetAuthTicketForWebApi tickets with Valve from trusted infrastructure, maps the returned SteamID64 to one durable Crux player, and gives that player structured saves, leaderboards, live config and other backend state that can outlive a lobby or server process.

Create a free Steam backend → Open the Steam auth quickstart

The Steam publisher Web API key stays server-side. Your player build receives only the normal publishable Crux key and creates short-lived Steam tickets through Steamworks.

Trust boundary Steam + Crux

Steam client
  GetAuthTicketForWebApi("crux")
          │ short-lived ticket
          ▼
Crux /v1/auth/steam
          │ server-only publisher key
          ▼
Valve AuthenticateUserTicket
          │ verified SteamID64
          ▼
Crux player_id
  saves / stats / leaderboards
  economy / live config / social

Verify before you integrate

Inspect the Steam boundary before you wire it into the game.

The client SDKs are MIT licensed, the auth routes are public OpenAPI, and the Steam publisher credential is kept behind the customer control plane rather than shipped in the game.

Live API status

A live check of the hosted API right now. No made-up uptime percentage and no hidden demo environment.

Check current status

Public API contract

The hosted HTTP surface is documented as OpenAPI. Inspect the wire format before choosing an SDK or writing an adapter.

Open the spec

MIT client SDKs

The JavaScript, Godot, Unity, and Roblox client SDK source is public. The hosted backend itself remains a managed proprietary service.

Inspect the SDK source

Documented exit path

Read what is exportable today and the written commitment for advance notice plus an export window if the hosted service winds down.

Read the exit guarantee

Steam SDK helpers

Use the JavaScript, Unity, Godot or Unreal helper for Steam ticket login/linking, or call the two public REST routes directly.

Inspect the Steam quickstart

Do not rebuild the Steam-native layer

Steamworks and a game backend solve different parts of the stack.

Steam already has identity tickets, lobbies, networking/SDR, Cloud, stats, Inventory and commerce surfaces. Crux is useful when your game needs a durable account/data/control layer beside those services, not as a reason to replace them.

Keep Steam-native

Steam account and Web API authentication ticket creation
Steam lobbies, friends/invites and Steam Datagram Relay
Steam Cloud when file sync fits your save model
Steam Inventory / Wallet flows when they fit your economy
Steam server discovery where it fits your dedicated-server model

Add in Crux where needed

Server-verified Steam ticket → stable game-owned player id
Structured/versioned cloud-save and project documents
Backend-owned stats, achievements and leaderboards
Trusted-server economy mutations and inventories
Live Config, social relationships and server registry

Native Steam ticket flow

No fake email. No client-supplied SteamID.

Configure the Steam App ID, publisher Web API key and ticket identity once in the Crux Credentials page. The key is write-only after save. A player build then asks Steamworks for a Web API ticket using that exact identity and sends only the ticket to Crux.

Crux verifies the ticket with Valve and keys your game data to the returned SteamID64 mapping. If the player already has guest/email/OAuth progress, use the link call instead of creating a second player.

Create the project and open Credentials → Steam player identity.
Store the Steam App ID and publisher Web API key; choose a ticket identity such as crux.
Call Steamworks GetAuthTicketForWebApi with that same identity from the game.
Hex-encode the returned ticket bytes and call the SDK loginSteam equivalent.
Use the returned Crux player_id for durable game-owned state.

Start the Steam path → Read the auth boundary

Account linking

Do not throw away the guest save when Steam becomes available.

POST /v1/auth/steam is a login: it resolves the Steam identity to its linked Crux player, creating one only on first use. POST /v1/auth/steam/link is different: it requires the existing player's Bearer token and attaches the verified Steam identity to that player. The mapping is one-to-one per project, so Crux refuses silent account merges.

See login/link code Guest upgrade architecture

Important boundary

Steam authentication does not mean “replace Steamworks.”

Crux does not proxy Steam Friends, replace Steam lobbies/SDR, mirror Steam Inventory, or allocate your entire dedicated-server fleet just because it can verify a Steam ticket. Keep each Steam-native service that fits. Use the verified identity bridge when a trusted game-owned backend needs to know which Steam account is making the request.

Read Steamworks vs game backend →

First useful test

Verify one real Steam player, then write one durable document.

That proves the only integration boundary that matters: Valve established the Steam identity, Crux resolved the stable game player, and your backend state is no longer keyed to an untrusted client-supplied SteamID.

Create the free Steam backend → Copy the Steam quickstart