One definition. Any technology. Any transport.
Model a stateful interface once with ObjectAPI — observable properties, callable operations, and server-pushed signals. Choose your target technology, then pick a transport per feature — OLink, MQTT, NATS, or extend the templates to target more, like gRPC — or keep it fully local. Unlike REST or OpenAPI, your definition stays the single source of truth: the service owns state, and clients sync or request changes.
How It Works
Define your interface in IDL or YAML — properties, operations, and signals. Choose your technology and pick a transport per feature, or stay fully local. Generate complete, buildable code with one command. Then iterate: regenerate anytime and your stub implementations are preserved while interface files stay in sync.
See It In Action
One stateful interface — properties, operations, and signals — becomes buildable code.
module climate 1.0
interface Thermostat {
// Properties (observable state)
temperature: float
targetTemp: float
isHeating: bool
// Operations (methods)
setTarget(float temp)
// Signals (server events)
signal overheated(float temp)
}
C++ shown. The same definition also generates Python, Qt, Unreal, Rust & Java.
Works with your AI coding agent
ApiGear's CLI runs as an MCP server, so AI assistants like Claude and Cursor can design interfaces, validate specs, and generate SDKs from a plain-English description — right inside your editor.
One platform: generate, simulate, monitor
ApiGear is a complete toolkit around your API definition.
Generate Production-Ready Code
From one definition, generate complete SDKs — interfaces, stub implementations, unit tests, and build files. Zero hand-written boilerplate.
Develop Without Dependencies
Simulate APIs before backends or hardware exist. Test integrations in isolation, ship frontend and backend in parallel — with traffic record & replay.
Debug with Full Visibility
Monitor every API call in real time. Trace property changes, operation calls, and signal emissions across your whole system.
Native Code for Every Platform
Generate idiomatic code for C++14, C++17, Qt6, Unreal Engine, Python, Rust, and Java. Each template follows its platform's conventions and best practices — and, depending on the template, features can run fully local or speak OLink, MQTT, or NATS.
Built For
Consistent APIs across languages and platforms — from prototype to production
Game Development
Generate Unreal Engine plugins from API specs. Decouple game logic from backend services and iterate faster.
Automotive & Embedded
Share consistent C++/Qt interfaces across ECUs. Simulate hardware APIs before the physical components exist.
Cross-Platform SDKs
Maintain one definition, generate native code for every platform, and keep implementations in sync automatically.
Define once. Generate everywhere.
Install the CLI and generate your first SDK in minutes — free and open source.