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FastAPI Payments Library

A flexible and extensible payment library for FastAPI applications supporting multiple payment providers and pricing models.

Features

• Multiple Payment Providers: Support for Stripe, PayPal, Adyen, PayU hosted checkout, and more
• Flexible Pricing Models:
  • Subscription
  • Usage-based
  • Tiered pricing
  • Per-user/seat pricing
  • Freemium
  • Dynamic pricing
  • Hybrid models
• Asynchronous Architecture: Built on FastAPI and SQLAlchemy 2.0 with async support
• Event-Driven: RabbitMQ integration via FastStream for reliable payment event messaging
• Highly Configurable: Extensive configuration options to customize for your needs
• Extensible: Easy to add new payment providers or custom pricing models

Installation

pip install fastapi-payments

Quick Start

from fastapi import FastAPI
from fastapi_payments import FastAPIPayments, create_payment_module
import json

# Create FastAPI app
app = FastAPI()

# Load payment configuration
with open("config/payment_config.json") as f:
    config = json.load(f)

# Initialize payments module
payments = FastAPIPayments(config)

# Include payment routes
payments.include_router(app, prefix="/api")

# Start server
if __name__ == "__main__":
    import uvicorn
    uvicorn.run(app, host="0.0.0.0", port=8000)

Configuration

Create a payment_config.json file:

{
  "providers": {
    "stripe": {
      "api_key": "sk_test_your_stripe_key",
      "webhook_secret": "whsec_your_webhook_secret",
      "sandbox_mode": true
    }
  },
  "database": {
    "url": "postgresql+asyncpg://user:password@localhost/payments"
  },
  "rabbitmq": {
    "url": "amqp://guest:guest@localhost/"
  },
  "pricing": {
    "default_currency": "USD",
    "default_pricing_model": "subscription"
  },
  "default_provider": "stripe"
}

PayU Hosted Checkout

To enable PayU hosted checkout add a payu provider:

"providers": {
  "payu": {
    "api_key": "your_merchant_key",
    "api_secret": "your_merchant_salt",
    "sandbox_mode": true,
    "additional_settings": {
      "success_url": "https://merchant.test/payu/success",
      "failure_url": "https://merchant.test/payu/failure",
      "cancel_url": "https://merchant.test/payu/cancel"
    }
  }
}

When calling POST /payments include the hosted checkout fields inside meta_info so the library can prepare the HTML form payload:

{
  "customer_id": "cust_123",
  "amount": 10.0,
  "currency": "INR",
  "meta_info": {
    "payu": {
      "firstname": "John",
      "email": "john@example.com",
      "phone": "9999999999",
      "productinfo": "Order #1001",
      "surl": "https://merchant.test/payu/success",
      "furl": "https://merchant.test/payu/failure"
    }
  }
}

The payment response includes meta_info.provider_data.payu.redirect containing the action URL and signed fields for rendering the hosted form. Webhooks posted by PayU can be sent using either JSON or form-encoded bodies and are verified automatically via the published hash logic.

Documentation

For complete documentation, visit https://fastapi-payments.readthedocs.io/

License

MIT