01 · Start

# Installation, in under a minute.

Reyn ships as a single Python package with no service to run. Install it, define a flow, and start orchestrating agents from your terminal.

## Requirements

Reyn supports Python 3.10 and later on Linux, macOS, and Windows. You'll also need an API key for the LLM provider you plan to use — `OPENAI_API_KEY`, `ANTHROPIC_API_KEY`, or any provider supported by the runtime.

## Install with pip

The fastest path is pip. Reyn has a small dependency footprint and installs in seconds.

terminal

    $ pip install reyn

Verify the install with the version command:

terminal

    $ reyn --version
    # reyn 0.4.2

Note

If you're on a managed Python environment, use `pipx install reyn` instead so the CLI lands on your PATH without polluting the system interpreter.

## Your first flow

A flow is a graph of phases. Each phase invokes one or more agents, and the runtime decides — based on LLM output — which phase to enter next.

flow.py

    from reyn import Flow, Agent

    researcher = Agent(
        name="researcher",
        skill="web_search",
    )

    writer = Agent(
        name="writer",
        skill="draft_summary",
    )

    flow = Flow("summarize")
    flow.add(researcher).then(writer)

    if __name__ == "__main__":
        flow.run(input="open-source AI orchestrators 2026")

Run it:

terminal

    $ python flow.py

### What just happened

- The `researcher` agent ran first, called the `web_search` skill, and produced a structured result.
- The runtime passed that result to the `writer` agent.
- Every step was logged to `~/.reyn/runs/` — replayable and inspectable.

Tip

Pass `--steer` to `reyn run` to pause between phases and approve, edit, or reject what the next agent sees.

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