> ## Documentation Index
> Fetch the complete documentation index at: https://docs.dodopayments.com/llms.txt
> Use this file to discover all available pages before exploring further.

# Vercel Functions

> Deploy DodoPayments webhooks to Vercel

<Card title="GitHub Repository" icon="github" href="https://github.com/dodopayments/cloud-functions/tree/main/vercel">
  Complete source code and setup guide
</Card>

## Quick Setup

### 1. Prerequisites

* [Vercel account](https://vercel.com/signup)
* [Neon database](https://neon.com) account
* DodoPayments API key from [dashboard](https://app.dodopayments.com/)

### 2. Install Dependencies

```bash theme={null}
npm install -g vercel
vercel login
git clone https://github.com/dodopayments/cloud-functions.git
cd cloud-functions/vercel
npm install
```

### 3. Database Setup

1. Sign up for [Neon](https://neon.com)
2. Create a new project
3. Open the SQL Editor
4. Copy and paste the contents of [`schema.sql`](#database-schema)
5. Run the query
6. Get your connection string from Neon → Connection Details

### 4. Set Initial Environment Variables

Via Vercel CLI:

```bash theme={null}
vercel env add DATABASE_URL
vercel env add DODO_PAYMENTS_API_KEY
```

> **Note:** We'll set `DODO_PAYMENTS_WEBHOOK_KEY` after deployment once you have your webhook URL.

### 5. Deploy

```bash theme={null}
npm run deploy
```

### 6. Get Your Webhook URL

Your webhook URL is:

```
https://[your-project].vercel.app/api/webhook
```

### 7. Register Webhook in DodoPayments Dashboard

1. Go to [DodoPayments Dashboard](https://app.dodopayments.com) → Developer → Webhooks
2. Create a new webhook endpoint
3. Configure your webhook URL as the endpoint
4. Enable these subscription events:
   * `subscription.active`
   * `subscription.cancelled`
   * `subscription.renewed`
5. Copy the **Signing Secret**

### 8. Set Webhook Key & Redeploy

```bash theme={null}
vercel env add DODO_PAYMENTS_WEBHOOK_KEY
npm run deploy
```

## What It Does

Processes subscription events and stores them in PostgreSQL:

* **subscription.active** - Creates/updates customer and subscription records
* **subscription.cancelled** - Marks subscription as cancelled
* **subscription.renewed** - Updates next billing date

## Key Features

✅ **Signature verification** - Using the dodopayments library\
✅ **Idempotency** - Prevents duplicate processing with webhook IDs\
✅ **Event logging** - Complete audit trail in `webhook_events` table\
✅ **Error handling** - Logged and retryable

> **Note:** This implementation demonstrates handling three core subscription events (`subscription.active`, `subscription.cancelled`, `subscription.renewed`) with minimal fields. You can easily extend it to support additional event types and fields based on your requirements.

## Configuration Files

<CodeGroup>
  ```json package.json theme={null}
  {
    "name": "dodo-webhook-vercel",
    "version": "1.0.0",
    "type": "module",
    "description": "DodoPayments Webhook Handler for Vercel",
    "scripts": {
      "start": "vercel dev",
      "deploy": "vercel --prod"
    },
    "dependencies": {
      "@neondatabase/serverless": "^1.0.2",
      "dodopayments": "^2.4.1"
    },
    "devDependencies": {
      "typescript": "^5.9.3",
      "vercel": "^48.4.1"
    }
  }
  ```

  ```json tsconfig.json theme={null}
  {
    "compilerOptions": {
      "target": "ES2022",
      "module": "ES2022",
      "lib": ["ES2022"],
      "moduleResolution": "node",
      "esModuleInterop": true,
      "strict": true,
      "skipLibCheck": true,
      "resolveJsonModule": true,
      "allowSyntheticDefaultImports": true,
      "forceConsistentCasingInFileNames": true,
      "isolatedModules": true,
      "types": ["node"]
    },
    "include": ["api/**/*.ts"],
    "exclude": ["node_modules"]
  }
  ```
</CodeGroup>

## Database Schema

<CodeGroup>
  ```sql schema.sql expandable theme={null}
  -- DodoPayments Webhook Database Schema
  -- Compatible with PostgreSQL (Supabase, Neon, etc.)

  -- Enable UUID extension (if not already enabled)
  CREATE EXTENSION IF NOT EXISTS "uuid-ossp";

  -- Customers table
  CREATE TABLE IF NOT EXISTS customers (
    id UUID PRIMARY KEY DEFAULT uuid_generate_v4(),
    email TEXT NOT NULL,
    name TEXT NOT NULL,
    dodo_customer_id TEXT UNIQUE NOT NULL,
    created_at TIMESTAMP WITH TIME ZONE DEFAULT NOW(),
    updated_at TIMESTAMP WITH TIME ZONE DEFAULT NOW()
  );

  -- Subscriptions table
  CREATE TABLE IF NOT EXISTS subscriptions (
    id UUID PRIMARY KEY DEFAULT uuid_generate_v4(),
    customer_id UUID NOT NULL REFERENCES customers(id) ON DELETE CASCADE,
    dodo_subscription_id TEXT UNIQUE NOT NULL,
    product_id TEXT NOT NULL,
    status TEXT NOT NULL CHECK (status IN ('pending', 'active', 'on_hold', 'cancelled', 'failed', 'expired')),
    billing_interval TEXT NOT NULL CHECK (billing_interval IN ('day', 'week', 'month', 'year')),
    amount INTEGER NOT NULL,
    currency TEXT NOT NULL,
    next_billing_date TIMESTAMP WITH TIME ZONE NOT NULL,
    cancelled_at TIMESTAMP WITH TIME ZONE,
    created_at TIMESTAMP WITH TIME ZONE NOT NULL,
    updated_at TIMESTAMP WITH TIME ZONE DEFAULT NOW()
  );

  -- Webhook events log
  CREATE TABLE IF NOT EXISTS webhook_events (
    id UUID PRIMARY KEY DEFAULT uuid_generate_v4(),
    webhook_id TEXT UNIQUE,
    event_type TEXT NOT NULL,
    data JSONB NOT NULL,
    processed BOOLEAN DEFAULT FALSE,
    error_message TEXT,
    created_at TIMESTAMP WITH TIME ZONE DEFAULT NOW(),
    processed_at TIMESTAMP WITH TIME ZONE,
    attempts INTEGER DEFAULT 0
  );

  -- Indexes for better query performance
  CREATE INDEX IF NOT EXISTS idx_customers_email ON customers(email);
  CREATE INDEX IF NOT EXISTS idx_customers_dodo_id ON customers(dodo_customer_id);
  CREATE INDEX IF NOT EXISTS idx_subscriptions_dodo_id ON subscriptions(dodo_subscription_id);
  CREATE INDEX IF NOT EXISTS idx_subscriptions_customer_id ON subscriptions(customer_id);
  CREATE INDEX IF NOT EXISTS idx_subscriptions_status ON subscriptions(status);
  CREATE INDEX IF NOT EXISTS idx_webhook_events_processed ON webhook_events(processed, created_at);
  CREATE INDEX IF NOT EXISTS idx_webhook_events_type ON webhook_events(event_type);
  CREATE INDEX IF NOT EXISTS idx_webhook_events_created_at ON webhook_events(created_at DESC);
  CREATE INDEX IF NOT EXISTS idx_webhook_events_webhook_id ON webhook_events(webhook_id);

  -- Function to automatically update updated_at timestamp
  CREATE OR REPLACE FUNCTION update_updated_at_column()
  RETURNS TRIGGER AS $$
  BEGIN
    NEW.updated_at = NOW();
    RETURN NEW;
  END;
  $$ LANGUAGE plpgsql;

  -- Triggers to automatically update updated_at
  CREATE TRIGGER update_customers_updated_at
    BEFORE UPDATE ON customers
    FOR EACH ROW
    EXECUTE FUNCTION update_updated_at_column();

  CREATE TRIGGER update_subscriptions_updated_at
    BEFORE UPDATE ON subscriptions
    FOR EACH ROW
    EXECUTE FUNCTION update_updated_at_column();

  -- Comments for documentation
  COMMENT ON TABLE customers IS 'Stores customer information from DodoPayments';
  COMMENT ON TABLE subscriptions IS 'Stores subscription data from DodoPayments';
  COMMENT ON TABLE webhook_events IS 'Logs all incoming webhook events for audit and retry purposes';

  COMMENT ON COLUMN customers.dodo_customer_id IS 'Unique customer ID from DodoPayments';
  COMMENT ON COLUMN subscriptions.dodo_subscription_id IS 'Unique subscription ID from DodoPayments';
  COMMENT ON COLUMN subscriptions.amount IS 'Amount in smallest currency unit (e.g., cents)';
  COMMENT ON COLUMN subscriptions.currency IS 'Currency used for the subscription payments (e.g., USD, EUR, INR)';
  COMMENT ON COLUMN webhook_events.attempts IS 'Number of processing attempts for failed webhooks';
  COMMENT ON COLUMN webhook_events.data IS 'Full webhook payload as JSON';
  ```
</CodeGroup>

**Tables created:**

* **customers** - Email, name, dodo\_customer\_id
* **subscriptions** - Status, amount, next\_billing\_date, linked to customers
* **webhook\_events** - Event log with webhook\_id for idempotency

## Implementation Code

<CodeGroup>
  ```typescript api/webhook/index.ts expandable theme={null}
  import { neon, NeonQueryFunction } from '@neondatabase/serverless';
  import { DodoPayments } from 'dodopayments';

  interface WebhookPayload {
    business_id: string;
    type: string;
    timestamp: string;
    data: {
      payload_type:
        | "Payment"
        | "Subscription"
        | "Refund"
        | "Dispute"
        | "LicenseKey"
        | "CreditLedgerEntry"
        | "CreditBalanceLow"
        | "AbandonedCheckout"
        | "DunningAttempt"
        | "EntitlementGrant";
      subscription_id: string;
      customer: {
        customer_id: string;
        email: string;
        name: string;
      };
      product_id: string;
      status: string;
      recurring_pre_tax_amount: number;
      payment_frequency_interval: string;
      created_at: string;
      next_billing_date: string;
      cancelled_at?: string | null;
      currency: string;
    };
  }

  // Disable body parsing to access raw body for webhook verification
  export const config = {
    api: {
      bodyParser: false,
    },
  };

  const corsHeaders = {
    'Access-Control-Allow-Origin': '*',
    'Access-Control-Allow-Headers': 'authorization, x-client-info, apikey, content-type, webhook-id, webhook-signature, webhook-timestamp',
    'Access-Control-Allow-Methods': 'POST, OPTIONS',
  };

  // Helper function for JSON responses
  function jsonResponse(data: unknown, status: number = 200) {
    return new Response(JSON.stringify(data), {
      status,
      headers: { ...corsHeaders, 'Content-Type': 'application/json' }
    });
  }

  // Handle subscription events
  async function handleSubscriptionEvent(sql: NeonQueryFunction<false, false>, payload: WebhookPayload, status: string) {
    if (!payload.data.customer.customer_id || !payload.data.subscription_id) {
      throw new Error('Missing required fields: customer_id or subscription_id');
    }

    console.log('🔄 Processing subscription event:', JSON.stringify(payload, null, 2));

    const customer = payload.data.customer;

    // Upsert customer (create if doesn't exist, otherwise use existing)
    const customerResult = await sql`
      INSERT INTO customers (email, name, dodo_customer_id, created_at)
      VALUES (${customer.email}, ${customer.name}, ${customer.customer_id}, ${new Date().toISOString()})
      ON CONFLICT (dodo_customer_id) 
      DO UPDATE SET 
        email = EXCLUDED.email,
        name = EXCLUDED.name,
        updated_at = ${new Date().toISOString()}
      RETURNING id
    `;

    const customerId = customerResult[0].id;
    console.log(`✅ Customer upserted with ID: ${customerId}`);

    // Upsert subscription
    await sql`
      INSERT INTO subscriptions (
        customer_id, dodo_subscription_id, product_id, status, 
        billing_interval, amount, currency, created_at, next_billing_date, cancelled_at, updated_at
      )
      VALUES (
        ${customerId}, ${payload.data.subscription_id},
        ${payload.data.product_id}, ${status},
        ${payload.data.payment_frequency_interval.toLowerCase()}, ${payload.data.recurring_pre_tax_amount},
        ${payload.data.currency}, ${payload.data.created_at}, ${payload.data.next_billing_date},
        ${payload.data.cancelled_at ?? null}, ${new Date().toISOString()}
      )
      ON CONFLICT (dodo_subscription_id) 
      DO UPDATE SET 
        customer_id = EXCLUDED.customer_id,
        product_id = EXCLUDED.product_id,
        status = EXCLUDED.status,
        billing_interval = EXCLUDED.billing_interval,
        amount = EXCLUDED.amount,
        currency = EXCLUDED.currency,
        created_at = EXCLUDED.created_at,
        next_billing_date = EXCLUDED.next_billing_date,
        cancelled_at = EXCLUDED.cancelled_at,
        updated_at = EXCLUDED.updated_at
    `;

    console.log(`✅ Subscription upserted with ${status} status`)
  }

  // Handle CORS preflight
  export async function OPTIONS() {
    return new Response('ok', { 
      status: 200,
      headers: corsHeaders 
    });
  }

  // Handle webhook POST request
  export async function POST(req: Request) {
    try {
      // Get raw body for webhook signature verification
      const rawBody = await req.text();
      
      console.log('📨 Webhook received');

      const DATABASE_URL = process.env.DATABASE_URL;
      const API_KEY = process.env.DODO_PAYMENTS_API_KEY;
      const WEBHOOK_KEY = process.env.DODO_PAYMENTS_WEBHOOK_KEY;

      if (!DATABASE_URL) {
        console.error('❌ Missing DATABASE_URL environment variable');
        return jsonResponse({ error: 'Server configuration error' }, 500);
      }

      // Verify required environment variables
      if (!API_KEY) {
        console.error('❌ DODO_PAYMENTS_API_KEY is not configured');
        return jsonResponse({ error: 'API key not configured' }, 500);
      }

      if (!WEBHOOK_KEY) {
        console.error('❌ DODO_PAYMENTS_WEBHOOK_KEY is not configured');
        return jsonResponse({ error: 'Webhook verification key not configured' }, 500);
      }

      // Verify webhook signature (required for security)
      const webhookHeaders = {
        'webhook-id': req.headers.get('webhook-id') || '',
        'webhook-signature': req.headers.get('webhook-signature') || '',
        'webhook-timestamp': req.headers.get('webhook-timestamp') || '',
      };

      try {
        const dodoPaymentsClient = new DodoPayments({
          bearerToken: API_KEY,
          webhookKey: WEBHOOK_KEY,
        });
        const unwrappedWebhook = dodoPaymentsClient.webhooks.unwrap(rawBody, { headers: webhookHeaders });
        console.log('Unwrapped webhook:', unwrappedWebhook);
        console.log('✅ Webhook signature verified');
      } catch (error) {
        console.error('❌ Webhook verification failed:', error);
        return jsonResponse({ error: 'Webhook verification failed' }, 401);
      }

      // Initialize Neon client
      const sql = neon(DATABASE_URL);

      const payload: WebhookPayload = JSON.parse(rawBody);
      const eventType = payload.type;
      const eventData = payload.data;
      const webhookId = req.headers.get('webhook-id') || '';

      console.log(`📋 Webhook payload:`, JSON.stringify(payload, null, 2));

      // Check for duplicate webhook-id (idempotency)
      if (webhookId) {
        const existingEvent = await sql`
          SELECT id FROM webhook_events WHERE webhook_id = ${webhookId}
        `;

        if (existingEvent.length > 0) {
          console.log(`⚠️ Webhook ${webhookId} already processed, skipping (idempotency)`);
          return jsonResponse({ success: true, message: 'Webhook already processed' });
        }
      }

      // Log webhook event with webhook_id for idempotency
      const logResult = await sql`
        INSERT INTO webhook_events (webhook_id, event_type, data, processed, created_at)
        VALUES (${webhookId || null}, ${eventType}, ${JSON.stringify(eventData)}, ${false}, ${new Date().toISOString()})
        RETURNING id
      `;

      const loggedEventId = logResult[0].id;
      console.log('📝 Webhook event logged with ID:', loggedEventId);

      console.log(`🔄 Processing: ${eventType} (${eventData.payload_type || 'unknown payload type'})`);

      try {
        switch (eventType) {
          case 'subscription.active':
            await handleSubscriptionEvent(sql, payload, 'active');
            break;
          case 'subscription.cancelled':
            await handleSubscriptionEvent(sql, payload, 'cancelled');
            break;
          case 'subscription.renewed':
            console.log('🔄 Subscription renewed - keeping active status and updating billing date');
            await handleSubscriptionEvent(sql, payload, 'active');
            break;
          default:
            console.log(`ℹ️ Event ${eventType} logged but not processed (no handler available)`);
        }

        await sql`
          UPDATE webhook_events 
          SET processed = ${true}, processed_at = ${new Date().toISOString()}
          WHERE id = ${loggedEventId}
        `;

        console.log('✅ Webhook marked as processed');
      } catch (processingError) {
        console.error('❌ Error processing webhook event:', processingError);

        await sql`
          UPDATE webhook_events 
          SET processed = ${false}, 
              error_message = ${processingError instanceof Error ? processingError.message : 'Unknown error'},
              processed_at = ${new Date().toISOString()}
          WHERE id = ${loggedEventId}
        `;

        throw processingError;
      }

      console.log('✅ Webhook processed successfully');

      return jsonResponse({
        success: true,
        event_type: eventType,
        event_id: loggedEventId
      });

    } catch (error) {
      console.error('❌ Webhook processing failed:', error);
      return jsonResponse({
        error: 'Webhook processing failed',
        details: error instanceof Error ? error.message : 'Unknown error'
      }, 500);
    }
  }
  ```
</CodeGroup>

## How It Works

The webhook handler:

1. **Disables body parsing** - To access raw body for signature verification
2. **Verifies the signature** - Ensures the request is from DodoPayments using HMAC-SHA256
3. **Checks for duplicates** - Uses webhook ID to prevent processing the same event twice
4. **Logs the event** - Stores raw webhook in `webhook_events` table for audit trail
5. **Processes the event** - Creates or updates customers and subscriptions in Neon
6. **Handles errors** - Logs failures and marks event as unprocessed for retry

## Testing

**Local development:**

```bash theme={null}
npm start
```

**View logs in Vercel Dashboard:**

1. Select your project
2. Go to **Deployments** → latest deployment
3. Click **Functions** → **Logs**

**Configure in DodoPayments Dashboard:**

1. Go to Developers → Webhooks
2. Add endpoint with your Vercel Functions URL
3. Enable: subscription.active, subscription.cancelled, subscription.renewed

## Common Issues

| Issue                     | Solution                                                            |
| ------------------------- | ------------------------------------------------------------------- |
| Verification failed       | Check webhook key is correct from DodoPayments dashboard            |
| Database connection error | Verify Neon connection string and use pooled connection             |
| Function timeout          | Optimize queries; Pro plan has longer timeout (60s)                 |
| Env vars not available    | Set in dashboard or CLI, ensure all environments selected, redeploy |

## Resources

* [Vercel Functions Docs](https://vercel.com/docs/functions)
* [Vercel CLI](https://vercel.com/docs/cli)
* [Neon Docs](https://neon.com/docs/)
* [Webhook Events Guide](/developer-resources/webhooks/intents/webhook-events-guide)
* [GitHub Repo](https://github.com/dodopayments/cloud-functions/tree/main/vercel)