Introduction

LetsFlow · the workflow engine developers love

LetsFlow is a lightweight workflow engine designed for processes that require both human involvement and automation. Unlike traditional workflow engines that rely on Directed Acyclic Graphs (DAGs) for fully automated workflows, LetsFlow is built on an extended finite-state machine model, offering flexibility for dynamic and non-linear processes.

With LetsFlow, you can define workflows where actors—real people—play a central role, while seamlessly integrating automated steps. This makes it ideal for scenarios like approval systems, customer service workflows, and collaborative processes, where decisions and actions often depend on human input.

YAML

schema: "https://specs.letsflow.io/v1.0.0/scenario"
title: My first scenario

actors:
  user:
    title: The user

actions:
  complete:
    title: Complete the process

states:
  initial:
    on: complete
    goto: (done)

JSON

{
    "schema": "https://specs.letsflow.io/v1.0.0/scenario",
    "title": "My first scenario",
    "actors": {
        "user": {
            "title": "user"
        }
    },
    "actions": {
        "complete": {
            "title": "Complete the process"
        }
    },
    "states": {
        "initial": {
            "action": "complete",
            "transition": "(done)"
        }
    }
}

The scenario models a process as a fine-state machine. The actors are persons, organizations, or systems that are allowed to participate in the process by performing actions. Which actions can be performed depends on the current state of the process. By executing an action, the process can transition to a different state.