---
id: automat
version: "25.4.16"
license: Copyright (c) 2014 Rackspace Permission is hereby granted, free of charge, to any person obtaining a copy of this software and associated documentation files (the "Software"), to deal in the Software… (full text in the JSON record)
license_treatment: permissive
maintenance: aging
---

# Automat — Self-service finite-state machines for the programmer on the go.

License: permissive · Maintenance: aging · Downloads: 14.3M/mo

## What it is and what it does

Automat is a finite-state machine library that lets you define stateful behavior using Python method calls and type protocols, rather than requiring you to pass generic input objects through a state engine. Instead of scattering conditional logic across methods to track state flags, you declare states and transitions upfront, and the library synthesizes a clean interface that enforces valid state sequences at runtime.

The library targets the common pattern where your code needs to behave differently depending on its state (like a coffee machine that should only brew when it has water, beans, and a closed lid), but your callers should not need to know or care that you've implemented it as a state machine. It depends only on typing_extensions and supports Python 3.9 through 3.13, with full type hints throughout.

Use it for:

- Implement protocol-based state machines for complex objects like network connections, protocol handlers, or device controllers that need strict state ordering.
- Build workflow engines or task schedulers where transitions between states must be explicit and validated at definition time.
- Create deterministic finite-state transducers that transform input sequences into output behaviors while maintaining clean, method-call-based APIs.
- Model state-dependent behavior in game logic, UI state management, or embedded systems where invalid state combinations must be impossible.
- Define type-safe state machines for async systems where each state transition can trigger side effects or return computed results.

## Worth the install?

AI-flagged interpretation of the facts above — verify before relying.

Automat provides a Python library for building finite-state machines using type-safe, method-based interfaces rather than generic input/output objects, letting you organize stateful behavior while keeping a clean API.

Yes, if you need to model stateful behavior with strict state ordering and want a clean, type-safe API. The permissive MIT license and low install friction make it low-risk. However, the 485-day gap since the last release suggests the project is aging; verify that it meets your Python version requirements (3.9+) and that its approach fits your use case before committing to it as a core dependency.

## Install

pip install automat
uv add automat
poetry add automat

## Installing Automat

Before you install: Low install friction with a single lightweight runtime dependency (typing_extensions). Maintenance status is aging—last release was 485 days ago, though the repository remains active with a recent commit on 2026-01-13 and 647 stars.

License in practice: MIT license (permissive) allows free use, modification, and distribution with minimal restrictions, making it suitable for both open-source and commercial projects.

Quickstart:

from automat import TypeMachineBuilder
from typing import Protocol

class MyStateMachine(Protocol):
    def event(self) -> None: pass

builder = TypeMachineBuilder(MyStateMachine, CoreData)
state_a = builder.state("state_a")
state_b = builder.state("state_b")
state_a.upon(MyStateMachine.event).to(state_b).returns(None)
machine = builder.build()

Requires Python 3.9 or later; familiarity with typing.Protocol and state machine concepts recommended.

Verify before relying:

- Whether the library is actively maintained or in maintenance-only mode given the 485-day gap since last release
- Performance characteristics and scalability limits for complex state machines with many states or transitions
- Real-world adoption patterns and whether it integrates well with async/await workflows

## Package facts

- License: Copyright (c) 2014 Rackspace Permission is hereby granted, free of charge, to any person obtaining a copy of this software and associated documentation files (the "Software"), to deal in the Software… (full text in the JSON record) (permissive)
- Python support: supports_current
- Install friction: low
- Maintenance: aging
- Downloads: 14.3M/month (top 5,000 on PyPI)
- Known vulnerabilities: none known

## Tags

finite state machine library, state machine python, fsm framework, typed state machines, deterministic automata, stateful behavior patterns, state transitions python, state-machine, type-safe, protocol-based

[View on SkillFed](https://skillfed.io/packages/automat) · [View on PyPI](https://pypi.org/project/automat/)