SpacetimeDB

SpacetimeDB is a relational database that also acts as the application server: developers upload their server logic into the database as a module, and game clients connect to it directly. Its maintainer, Clockwork Labs, puts it this way in the project README: "You upload your application logic directly into the database, and clients connect to it without any server in between." For multiplayer games that removes the usual three-part stack of game server, database and synchronisation layer, which is why it has become a talking point among gaming backends even though it is a general-purpose system.

The database-as-server model

A SpacetimeDB application is a set of tables plus functions that run inside the database. The documentation groups those functions as reducers, procedures and views; clients call them to change state and register subscriptions to be told when the rows they care about change. Because the logic runs next to the data inside a transaction, there is no separate service to deploy and no cache to keep consistent. The vendor describes the system as "a general purpose relational database with strongly serializable ACID transactions, that takes stored procedures to the next level".

Modules can be written in Rust, C#, TypeScript or C++ according to the GitHub README (fetched October 6, 2026). Client SDKs cover TypeScript with the major web frameworks, Rust, C# including Unity, and C++ for Unreal Engine. The best-known production user is the MMO BitCraft: the SpacetimeDB homepage carries a description of it as "a database and server in one" used "to power the entire backend of BitCraft, including real-time multiplayer".

Performance claims should be read as the vendor's own. The homepage says deploying logic into the database yields "100x-1000x better performance" and shows benchmarks against conventional stacks; these are vendor-run comparisons, not independent tests.

Licensing: source-available, not open source

SpacetimeDB's code is public on GitHub (25.3k stars as of October 6, 2026), but it is not released under an open-source licence. The licence file names Clockwork Laboratories, Inc. as licensor of SpacetimeDB 2.11.0 under the Business Source License 1.1, with these terms:

In practice a studio can read the code, run it locally and run a single production instance itself. Running more than that, or offering it as a hosted database service, requires a commercial arrangement until the version converts to AGPL. The linking exception is intended to keep a studio's own module code out of the AGPL's reach. Teams with strict open-source requirements should compare this with Nakama, whose server is Apache-2.0.

Hosting and pricing

The managed service is called Maincloud and is billed in an energy unit the company calls TeV. As listed on spacetimedb.com/pricing on October 6, 2026:

A standalone server is available for local development; the documentation notes that standalone mode does not support SSL.

Where it fits

SpacetimeDB suits games built around a shared, persistent, constantly changing world, where the hard problem is keeping many clients consistent with one authoritative state. It also suits small teams that would rather write table definitions and reducers than operate a fleet of services, and the company now pitches it at agent-written software as "a reactive backend platform that AI agents love".

It is a less obvious choice when a studio wants packaged game features. The vendor's own description lists database, server logic, auth, deployment and real-time sync; economies, tournaments or a LiveOps console are things a team models itself as tables and reducers, whereas platforms such as PlayFab or Nakama ship them as services. The single-instance production grant is the other thing to check early. A direct comparison of the two models is in Nakama vs SpacetimeDB.