iii-hq/iii

What is it?

Key features

• 01Registers any process as a worker that exposes functions to the rest of the system.
• 02Supports HTTP, cron, queue, state and stream triggers that invoke functions declaratively.
• 03Adds workers at runtime through a Compose daemon, so new capabilities join without restarts.
• 04Provides official SDKs for Node.js, Python, Rust and Go.
• 05Includes a console for inspecting workers, functions, triggers, queues, traces and logs.

Use cases

• Connecting microservices written in different languages through one set of callable functions.
• Giving AI agents a shared catalog of capabilities they can discover, call and trace.
• Replacing separate queue, cron and HTTP integrations with one trigger model.
• Tracing and debugging calls across services in one view.

Quick start

1. 1

   Install the iii CLI

   Install with the official instructions in the README
2. 2

   Start a Compose namespace with workers

   iii compose --namespace dev --up
3. 3

   Add a worker to the running system

   iii trigger -n dev compose::add worker=queue

Things to know

• !The engine is licensed under the Elastic License 2.0, which is source-available rather than OSI open source.
• !Only the SDKs, CLI, console and docs are Apache 2.0, so check the engine license before commercial use.

Topics

FAQ

What is iii?

A Rust runtime that lets services, workers, queues, cron jobs and agents be composed, discovered and traced through one live function catalog. iii is an engine for building backends out of small units called workers, functions and triggers. A worker is any process that registers with the iii engine, such as a TypeScript API service, a Python pipeline or a Rust microservice. Functions have stable identifiers, and triggers declare when they run: a direct call, an HTTP endpoint, a cron schedule, a queue subscription or a state change. The engine handles routing, serialization and delivery.

Is iii free to use? What license does it have?

iii has no declared license. Its code is public, but without a license you have no explicit permission to reuse it; ask the author before relying on it.

Is iii still maintained?

Actively maintained. The last commit to iii was on Oct 19, 2026.

What can I use iii for?

Connecting microservices written in different languages through one set of callable functions. Giving AI agents a shared catalog of capabilities they can discover, call and trace. Replacing separate queue, cron and HTTP integrations with one trigger model. Tracing and debugging calls across services in one view.

How do I install iii?

Install the iii CLI Start a Compose namespace with workers: iii compose --namespace dev --up Add a worker to the running system: iii trigger -n dev compose::add worker=queue

Where can I get iii?

The source code and installation instructions are on GitHub: https://github.com/iii-hq/iii