Billing - Sendook

Overview

Sendook uses usage-based billing powered by Stripe. You only pay for the emails you send and receive.

Pricing Model

Sendook charges based on email usage with no upfront costs or monthly minimums.

What’s Metered

Billing is calculated on:

Messages sent - Each outbound email from your inboxes
Messages received - Each inbound email to your inboxes

Webhook deliveries, API calls, and dashboard usage are not metered or charged.

Billing Period

Charges are calculated monthly:

Billing period - First day to last day of each calendar month
Invoice generation - Invoices are created at the end of each billing period
Payment - Automatic payment from your saved payment method

Stripe Integration

Sendook is fully integrated with Stripe for secure payment processing.

Setting Up Billing

On Registration When you sign up, Sendook automatically:

Creates a Stripe customer account
Creates a subscription with usage-based pricing
Links your organization to the Stripe customer

Adding a Payment Method

Log in to the dashboard
Navigate to Billing
Click Add Payment Method
Enter your card details in the Stripe form
Add your billing address
Click Add Payment Method

Sendook uses Stripe Elements for secure card collection. Your card details never touch Sendook’s servers.

Required Environment Variables

For self-hosted deployments, configure these Stripe environment variables:

STRIPE_SECRET_KEY=sk_test_... # Your Stripe secret key
STRIPE_WEBHOOK_SECRET=whsec_... # Stripe webhook signing secret
STRIPE_PRICE_ID=price_... # Your usage-based price ID
STRIPE_PRODUCT_ID=prod_... # Your product ID
STRIPE_METER_EVENT=email_sent # Meter event name for tracking usage

Usage Tracking

Sendook tracks usage in real-time using Stripe’s billing meters.

How It Works

Message sent/received - Your application sends or receives an email

Meter event created - Sendook sends a meter event to Stripe:

stripe.billing.meterEvents.create({
  event_name: process.env.STRIPE_METER_EVENT,
  timestamp: Math.floor(Date.now() / 1000),
  payload: {
    stripe_customer_id: customerId,
    value: "1"
  }
});

Usage aggregated - Stripe aggregates all events for the billing period
Invoice generated - At period end, Stripe creates an invoice based on total usage

Viewing Usage

In the dashboard:

Navigate to Billing
View Current Month Invoice
See accumulated charges for the current period

Invoice details show:

Current status (Draft, Open, Paid)
Amount due
Billing period dates
Link to detailed invoice in Stripe

Payment Methods

Supported Payment Types

Credit cards (Visa, Mastercard, American Express)
Debit cards
Additional methods supported by Stripe

Managing Payment Methods

Updating Your Card

Go to Billing in the dashboard
Click Update next to your current payment method
Enter new card details
Submit the form

The new card becomes your default payment method immediately. Payment Method Details Your saved payment method shows:

Card brand and last 4 digits
Expiration date
Billing address

Keep your payment method up to date. Failed payments may result in service interruption.

Invoices

Invoice Lifecycle

Draft - Invoice being calculated during billing period
Open - Invoice finalized and awaiting payment
Paid - Payment successfully processed
Uncollectible - Payment failed after retries
Void - Invoice cancelled

Accessing Invoices

Via Dashboard

Navigate to Billing
Click View Invoice to open in Stripe
Download PDF or view details

Via API Retrieve the current month’s invoice:

curl https://api.sendook.com/organizations/{organization_id}/payment_methods/invoice/current \
  -H "Authorization: Bearer YOUR_ACCESS_TOKEN"

Response:

{
  "invoice": {
    "id": "in_abc123",
    "amount_due": 1500,
    "currency": "usd",
    "status": "paid",
    "period_start": 1709251200,
    "period_end": 1711929599,
    "hosted_invoice_url": "https://invoice.stripe.com/i/..."
  }
}

Invoice History

Access past invoices:

curl https://api.sendook.com/organizations/{organization_id}/payment_methods/invoices?limit=10 \
  -H "Authorization: Bearer YOUR_ACCESS_TOKEN"

Stripe Customer Management

Each organization is linked to a Stripe customer.

Customer Creation

When you register, Sendook creates a Stripe customer:

const customer = await stripe.customers.create({
  name: organizationName,
  email: userEmail
});

Subscription Creation

A subscription is automatically created with your usage-based price:

const subscription = await stripe.subscriptions.create({
  customer: customerId,
  items: [{ price: process.env.STRIPE_PRICE_ID }]
});

Payment Method Attachment

When you add a payment method:

Create a Setup Intent:

const setupIntent = await stripe.setupIntents.create({
  customer: customerId,
  payment_method_types: ['card']
});

Confirm on client side with Stripe Elements

Attach the payment method:

await stripe.paymentMethods.attach(paymentMethodId, {
  customer: customerId
});

Self-Hosting Billing

If you’re self-hosting Sendook, you’ll need to set up your own Stripe account.

Prerequisites

Stripe Account - Sign up at stripe.com
Product & Price - Create a product with usage-based pricing
Billing Meter - Set up a meter for tracking email usage
Webhook Endpoint - Configure webhook for payment events

Setup Steps

1. Create Stripe Product In your Stripe dashboard:

Go to Products
Click “Add product”
Select “Usage based” pricing
Set your per-unit price
Save the product ID and price ID

2. Create Billing Meter

Go to Billing → Meters
Create a new meter (e.g., “email_sent”)
Note the meter event name

3. Configure Environment Variables Add to your .env file:

STRIPE_SECRET_KEY=sk_live_your_key
STRIPE_WEBHOOK_SECRET=whsec_your_secret
STRIPE_PRICE_ID=price_your_price_id
STRIPE_PRODUCT_ID=prod_your_product_id
STRIPE_METER_EVENT=email_sent

4. Set Up Webhooks Configure Stripe webhook to point to:

https://your-domain.com/webhook/stripe

Subscribe to events:

invoice.payment_succeeded
invoice.payment_failed
customer.subscription.updated
customer.subscription.deleted

The webhook secret is required to verify webhook signatures. Never commit it to version control.

API Integration

Get Payment Method

curl https://api.sendook.com/organizations/{organization_id}/payment_methods \
  -H "Authorization: Bearer YOUR_ACCESS_TOKEN"

Create Setup Intent

curl -X POST https://api.sendook.com/organizations/{organization_id}/payment_methods/setup-intent \
  -H "Authorization: Bearer YOUR_ACCESS_TOKEN" \
  -H "Content-Type: application/json"

Attach Payment Method

curl -X POST https://api.sendook.com/organizations/{organization_id}/payment_methods/attach \
  -H "Authorization: Bearer YOUR_ACCESS_TOKEN" \
  -H "Content-Type: application/json" \
  -d '{"paymentMethodId": "pm_abc123"}'

Troubleshooting

Payment Failed

If a payment fails:

Check that your card is valid and has sufficient funds
Update your payment method in the dashboard
Contact your bank if the card is declined
Stripe will automatically retry failed payments

No Invoice Showing

Invoices are generated at the end of each billing period
During the month, you’ll see a “Draft” invoice
If no usage, no invoice will be generated

Incorrect Usage Amount

Check the meter events in Stripe dashboard
Verify STRIPE_METER_EVENT is set correctly
Look for failed meter event submissions in logs

Can't Add Payment Method

Ensure Stripe publishable key is configured
Check browser console for Stripe errors
Verify billing address is complete
Try a different card or payment method

Cost Optimization

Monitor Usage

Regularly check your current month invoice to track spending trends.

Set Up Alerts

Configure Stripe billing alerts to notify you when spending exceeds thresholds.

Optimize Workflows

Review your email workflows to reduce unnecessary messages.

Test in Development

Use a separate organization with a test Stripe account for development.

Next Steps

Dashboard

Learn how to manage billing in the dashboard

API Reference

Integrate billing into your application

Self-Hosting

Set up billing for self-hosted deployments

Authentication

Secure your API access

Get Started

Core Features

Guides

​Overview

​Pricing Model

​What’s Metered

​Billing Period

​Stripe Integration

​Setting Up Billing

​Required Environment Variables

​Usage Tracking

​How It Works

​Viewing Usage

​Payment Methods

​Supported Payment Types

​Managing Payment Methods

​Invoices

​Invoice Lifecycle

​Accessing Invoices

​Invoice History

​Stripe Customer Management

​Customer Creation

​Subscription Creation

​Payment Method Attachment

​Self-Hosting Billing

​Prerequisites

​Setup Steps

​API Integration

​Get Payment Method

​Create Setup Intent

​Attach Payment Method

​Troubleshooting

​Cost Optimization

Monitor Usage

Set Up Alerts

Optimize Workflows

Test in Development

​Next Steps

Dashboard

API Reference

Self-Hosting

Authentication

Build docs developers (and LLMs) love

Overview

Pricing Model

What’s Metered

Billing Period

Stripe Integration

Setting Up Billing

Required Environment Variables

Usage Tracking

How It Works

Viewing Usage

Payment Methods

Supported Payment Types

Managing Payment Methods

Invoices

Invoice Lifecycle

Accessing Invoices

Invoice History

Stripe Customer Management

Customer Creation

Subscription Creation

Payment Method Attachment

Self-Hosting Billing

Prerequisites

Setup Steps

API Integration

Get Payment Method

Create Setup Intent

Attach Payment Method

Troubleshooting

Cost Optimization

Next Steps