# Paysera Checkout Classic - API Reference

> Paysera Checkout Classic is the established payment integration using MAC authentication. For new integrations, we recommend [Checkout (New)](/llms-checkout.txt) for its modern features.

## About Checkout Classic

Checkout Classic is our proven payment integration that has served merchants reliably for years. While we recommend Checkout (New) for new integrations due to its modern architecture and features, Checkout Classic remains fully supported.

## Key Differences from Checkout (New)

| Aspect | Checkout Classic | Checkout (New) |
|--------|------------------|----------------|
| Authentication | MAC signatures | OAuth2 Bearer tokens |
| Architecture | Monolithic | Microservices |
| Amount Format | Cents as integers | String in request, Long in response |
| Status Updates | Callback with MAC | Webhooks with HMAC-SHA256 |

## Base URLs

| Environment | URL |
|-------------|-----|
| Production | https://www.paysera.com/pay/ |
| Sandbox | https://sandbox.paysera.com/pay/ |

## Documentation

For complete legacy Checkout documentation, see:
- Documentation: https://developers.paysera.com/checkout/classic/
- Migration Guide: Contact developer-support@paysera.com

## Support

- Documentation: https://developers.paysera.com
- Support: developer-support@paysera.com