Recover & Grow Subscription Revenue

Start a workflow. We handle the rest. Pre-built workflows recover payments, convert trials, and retain subscribers.

Install the SDK and start recovering revenue in minutes.

1npm install @fourbyfour/sdk

123456import { fbf } from '@fourbyfour/sdk'; const client = fbf({  apiKey: process.env.FOURBYFOUR_API_KEY!,  projectId: process.env.FOURBYFOUR_PROJECT_ID!,});

Get your API key from the dashboard. 8 pre-built workflows across 4 intent categories are ready to use.

Two functions. Intent-based workflows.

12345678910// Payment failed → triggers recovery workflowawait client.startWorkflow({  userId: 'cus_9s6XGrhLkFm2pQ',  intent: 'PAYMENT_FAILED',  signals: {    amountCents: 9900,    reason: 'card_expired',    currency: 'USD',  },});

12345// When payment is recoveredawait client.resolveConversion({  userId: 'cus_9s6XGrhLkFm2pQ',  amount: 99.00,});

Answer a few questions about your stack and we'll generate a step-by-step integration guide that you can feed to your AI coding assistant (Claude Code, Cursor, Copilot, etc.).

Two functions. Intent-based. Fully typed.

12345678910// Start a workflow with intent and signalsawait client.startWorkflow({  userId: 'cus_9s6XGrhLkFm2pQ',  intent: 'PAYMENT_FAILED',  signals: {    amountCents: 9900,    reason: 'card_expired',    retryCount: 1,  },});

12345// Record successful conversion (payment recovered)await client.resolveConversion({  userId: 'cus_9s6XGrhLkFm2pQ',  amount: 99.00,});

12345678910// PAYMENT_FAILED signalssignals: {  amountCents: number;        // Required  reason: 'insufficient_funds' | 'card_expired' | 'declined' | 'error';  currency?: string;          // Optional  retryCount?: number;  plan?: { id: string; name: string };  tenureMonths?: number;  ltvCents?: number;}

8 intents across 4 categories. Each with typed signals.

{
  id: string;      // Your plan ID
  name: string;    // Display name
  priceCents?: number;  // Price in cents
  tier?: string;   // "starter" | "pro" | "enterprise"
}

Just-in-time PII. Your data stays in your system until the moment of delivery.

1234567891011POST /api/fourbyfour/resolveHeaders:  x-fbf-signature: sha256=... Body:{  "userId": "cus_9s6XGrhLkFm2pQ",  "fields": ["email", "name"],  "workflowId": "payment-recovery",  "channel": "email"}

123456789101112HTTP 200 OK {  "email": "user@example.com",  "name": "John"} // Or if user not found:HTTP 404 Not Found{  "error": "User not found"}

12345678910111213141516171819202122232425// Express / Next.js API routeapp.post('/api/fourbyfour/resolve', async(req, res) => {  // Verify the request is from Fourbyfour  const signature = req.headers['x-fbf-signature'];  if(!verifySignature(signature, req.body, process.env.FBF_WEBHOOK_SECRET)) {    return res.status(401).json({ error: 'Invalid signature' });  }   const { userId, fields, workflowId, channel } = req.body;   // Fetch user from your database  const user = await db.users.findById(userId);  if(!user) {    return res.status(404).json({ error: 'User not found' });  }   // Return only requested fields  const response: Record<string, string> = {};   if(fields.includes('email')) response.email = user.email;  if(fields.includes('name')) response.name = user.firstName;  if(fields.includes('phone')) response.phone = user.phone;   res.json(response);});

8 subscription revenue workflows. Track the event, we handle timing, channels, and intelligent messaging.

We deliver via the optimal channel. You just provide the resolver endpoint. We handle the rest.