What external integrations have you worked with?

External integrations can be very diverse depending on the domain and project. Here are some examples that are often encountered:

• Third-party service APIs: integration with payment systems (Stripe, PayPal), delivery services (DHL, FedEx), social networks (Facebook, VK), cloud providers (AWS, Azure).
• Databases and storage: connection to SQL/NoSQL databases, caches (Redis, Memcached).
• Authentication and authorization systems: OAuth, LDAP, SSO.
• Messengers and notifications: integration with Telegram, Slack, email services.
• Monitoring and analytics: Prometheus, Grafana, Google Analytics.

When working with integrations, it is important to consider:

• Data formats (JSON, XML, protobuf).
• Reliability and error handling.
• Security and authentication.
• Performance and request limits.

For example, when integrating with a payment system, it is necessary to implement callback notification processing, payment status verification, and proper error handling.