Iii

What is iii

You start building a backend and immediately need six different tools: an API framework, a task queue, a cron scheduler, pub/sub, a state store, and an observability pipeline. Each has its own config, its own deployment, its own failure modes. A simple "process this, then notify that" workflow touches three services before you write any business logic.

iii replaces all of that with a single engine and three primitives: Function, Trigger, and Worker.

A Function is anything that does work. A Trigger is what causes it to run - an HTTP request, a cron schedule, a queue message, a state change. A Worker connects your functions to the engine. You write the function, declare what triggers it, connect a worker, and the engine handles routing, retries, and observability.

One config file. One process. Everything discoverable. Think of it the way React gave frontend a single model for UI - iii gives your backend a single model for execution.

Three Concepts

| Concept | What it does | | ------------- | ------------ | | Function | A unit of work. It receives input and optionally returns output. It can exist anywhere: locally, in the cloud, on serverless, or as a third-party HTTP endpoint. | | Trigger | What causes a Function to run - explicitly from code, or automatically from an event source. Examples: HTTP route, cron schedule, queue topic, state change, stream event. | | Worker | The runtime that connects your functions and triggers to the engine. Workers register and deregister themselves without configuration. Once connected, their functions are available across the entire backend. |

Quick Start

Get started with iii by following the Quickstart guide.

SDKs

| Language | Package | Install | | -------- | -------------------------------------------------- | --------------------- | | Node.js | iii-sdk | npm install iii-sdk | | Python | iii-sdk | pip install iii-sdk | | Rust | iii-sdk | Add to Cargo.toml |

Console

The iii-console is a developer and operations dashboard for inspecting functions, triggers, traces, and real-time state. See the Console docs for setup and usage.

Repository Structure

| Directory | What it is | README | | -------------- | ------------------------------------------------------- | --------------------------------------- | | engine/ | iii Engine (Rust) - core runtime, modules, and protocol | engine/README.md | | sdk/ | SDKs for Node.js, Python, and Rust | sdk/README.md | | console/ | Developer dashboard (React + Rust) | console/README.md | | frameworks/ | Higher-level frameworks built on the SDK | frameworks/motia/ | | website/ | iii website | website/ | | docs/ | Documentation site (Mintlify/MDX) | docs/README.md |

See STRUCTURE.md for the full monorepo layout, dependency chain, and CI/CD details.

Examples

See the Quickstart guide for step-by-step tutorials.

Resources

• Documentation
• CLI & Engine
• Console
• Examples
• Contributing

License

The iii project uses a dual licensing model:

| Directory | License | | ---------------- | -------------------- | | engine/ | Elastic License 2.0 | | sdk/ | Apache License 2.0 | | cli/ | Apache License 2.0 | | console/ | Apache License 2.0 | | frameworks/ | Apache License 2.0 | | docs/ | Apache License 2.0 | | website/ | Apache License 2.0 |

The engine runtime is licensed under the Elastic License 2.0 (ELv2). All SDKs, frameworks, CLI, console, documentation, and the website are licensed under the Apache License 2.0.

See NOTICE.md for details.