Overview - Spacetimedb

The SpacetimeDB Client SDKs provide a comprehensive interface for building applications that connect to SpacetimeDB databases. Client applications can query data, invoke server-side functions, and receive real-time updates as the database state changes.

Available SDKs

SpacetimeDB provides client SDKs for multiple languages:

Getting Started

To build a client application with SpacetimeDB:

Generate client bindings - Use spacetime generate to create type-safe bindings for your database
Connect to your database - Establish a WebSocket connection to SpacetimeDB
Use the SDK API - Subscribe to data, invoke functions, and register callbacks

Core Capabilities

Connection Management

The SDKs handle establishing and maintaining WebSocket connections to SpacetimeDB servers. Connections support authentication via tokens (for example, from SpacetimeAuth) and provide lifecycle callbacks for connect, disconnect, and error events.

See Connecting to SpacetimeDB for details.

Client-Side Data Cache

Each client maintains a local cache of database rows through subscriptions. Clients define which data they need using SQL queries, and SpacetimeDB automatically synchronizes changes to the subscribed data. The local cache can be queried without network round-trips, providing fast access to frequently-read data.

Real-Time Updates

Clients receive automatic updates when subscribed data changes. The SDKs provide callbacks for observing:

Subscription updates - When subscription queries are applied or fail
Row changes - When rows are inserted, updated, or deleted in the local cache
Reducer invocations - When reducers run on the server
Procedure results - When procedures are called the results are returned via a callback

Invoking Server Functions

Clients can invoke server-side functions to modify data or perform operations:

Reducers - Transactional functions that modify database state
Procedures - Functions that can perform external operations like HTTP requests (beta)

Type Safety

The generated client bindings provide compile-time type safety between your client and server code. Table schemas, function signatures, and return types are all reflected in the generated code, catching errors before runtime.

Choosing a Language

When selecting a language for your client application, consider these factors:

Team Expertise

Choose a language your development team is comfortable with to maximize productivity and reduce development time.

Application Type

Web applications - TypeScript integrates seamlessly with browser and Node.js environments
Desktop applications - Rust or C# depending on your platform and requirements
Performance-critical applications - Rust offers the best performance and memory efficiency
Unity games - C# is required for Unity development
Unreal games - C++ and Blueprint are both supported for Unreal clients

Platform and Ecosystem

Each language has its own ecosystem of libraries and tools. If your application depends on specific libraries or frameworks, that may influence your choice.

The functionality of the SDKs remains consistent across languages, so transitioning between them primarily involves syntax changes rather than architectural changes. You can even use multiple languages in the same project - for example, C# for a Unity game client and TypeScript for a web administration panel.

Learning Path

New to SpacetimeDB client development? Follow this progression:

Generate Client Bindings - Create type-safe interfaces from your module
Connect to SpacetimeDB - Establish a connection and understand the lifecycle
Use the SDK API - Learn about subscriptions, reducers, and callbacks
Language Reference - Dive into language-specific details: Rust, C#, TypeScript

Next Steps

Follow a Quickstart guide Rust, C#, or TypeScript to build your first client
Learn about Databases to understand what you're connecting to
Explore Subscriptions for efficient data synchronization
Review Reducers to understand server-side state changes