# Environment & Testing

- [Sandbox and production URLs](/faqs-and-troubleshooting/environment-and-testing/sandbox-and-production-urls.md)
- [Test data: email address requirements](/faqs-and-troubleshooting/environment-and-testing/test-data-email-address-requirements.md)
- [Crypto payments, environment and testing](/faqs-and-troubleshooting/environment-and-testing/crypto-payments-environment-and-testing.md)
- [USDC network fees and cost considerations](/faqs-and-troubleshooting/environment-and-testing/usdc-network-fees-and-cost-considerations.md)
- [How to Test Klarna Payments](/faqs-and-troubleshooting/environment-and-testing/how-to-test-klarna-payments.md)