Refluxo 🔀⚙️🔁🛠️

A stateless, snapshot‑based, and serverless‑ready workflow engine for JavaScript.

Refluxo is a lightweight engine designed for modern distributed environments. Unlike traditional engines that "run" a process, Refluxo transitions states. It takes a snapshot, processes a step, and returns a new snapshot. This makes it the perfect backbone for "Human-in-the-loop" systems, long-running processes, and serverless architectures.

"Build your own n8n or Zapier-like automation platform with ease."

✨ Features

🌐 Runs anywhere

Refluxo is isomorphic. It runs wherever JavaScript runs:

• Serverless: Designed to run on AWS Lambda, Cloudflare Workers, Vercel, etc. No background processes required.
• Runtime: Node.js, Bun, Deno.
• Browser: React, Vue, Svelte, or vanilla JS.

📸 Snapshot-Based

Every execution step is serializable. Pause a flow, save it to a database, and resume it days later.

🛡️ Validation & Strict Schemasype Safety

Refluxo supports any validation library that implements Standard Schema. You can use the popular Zod, Valibot for a small bundle size, TypeBox or ArkType for better peformance, or any other.

If you store your schema outside code, like in a database, you can write a logic to convert it to a Standard Schema object, for a example, read the docs

🧠 Powerful Expressions

Uses JEXL to allow dynamic data mapping similar to n8n.

⏸ Human-in-the-loop

Built-in support for external triggers and manual approvals via externalPayload.

🔁 Smart Retries

Define dynamic retry policies (fixed or exponential backoff) using expressions.

📦 Installation

pnpm add refluxo-engine

💡 Usage Examples

🔧 1. Defining Node Executors

Executors are pure logic. They receive resolved data and return an output.

import { NodeDefinition } from 'refluxo-engine';
import * as v from 'valibot'; // or any other

const httpRequest: NodeDefinition = {
  input: v.object({
    url: v.pipe(v.string(), v.url())
  }),
  
  async executor(data, context) {
    const response = await fetch(data.url);
    const json = await response.json();
    return { data: json };
  },
};

🏗️ 2. Workflow Definition

Workflows are plain JSON objects, making them easy to store and fetch from a frontend or database.

const workflow = {
  nodes: [
    { id: 'start', type: 'http_request', data: { url: 'https://api.example.com/data' } },
    data: { check: '{{ nodes.start.last.data.status === "ok" }}' }
  ],
  edges: [
    { source: 'start', target: 'check_status' },
    { source: 'check_status', target: 'notify_node', sourceHandle: 'true' }
  ]
};

⏸ 3. Pause & Resume (Human-in-the-loop)

You can pause execution to wait for an event or manual approval.

// In your executor
async executor(data, context, externalPayload) {
  if (!externalPayload) {
    return { data: {}, __pause: true }; // Engine will stop here
  }
  return { data: externalPayload }; // Resumes with the payload
}

// Executing
const engine = new WorkflowEngine({ workflow, nodeDefinitions });
let snapshot = await engine.execute({ initialNodeId: 'start' });

// ... later, when the user approves ...
snapshot = await engine.execute({ 
  snapshot, 
  externalPayload: { approvedBy: 'admin_id' } 
});

🔄 Smart Retry Policies

Retries can be static or dynamic, driven by expressions.

const apiNode = {
  type: 'api_call',
  retryPolicy: {
    maxAttempts: 'nodes.config.last.data.retryCount',
    interval: 5000,
    backoff: 'exponential'
  },
  // ...
};

🚀 Why Refluxo?

• Stateless by Design: No need for a persistent event loop. The state is in your database, not in memory.
• Highly Extensible: Replace the Expression Engine or the Validation logic easily.
• Traceable: Metadata tracks totalExecutionTime, attempts, and every node output, making debugging a breeze.
• Developer Friendly: Built with TypeScript for full type safety.

📝 Use Cases

• Automation Platforms: Build a custom Zapier/n8n for your niche.
• Approval Workflows: Systems that require human intervention (e.g., Expense approval).
• Scheduled Tasks: Flows that wait for a specific date or time to continue.
• Complex Orchestration: Microservices coordination with automatic retries.