What types of systems or services have you integrated into your previous projects?

In my projects, I have integrated various types of systems and services, including:

• External REST APIs for data retrieval or sending information (e.g., integration with payment systems, weather services, social networks).
• Databases (SQL and NoSQL) for storing and retrieving data.
• Authentication and authorization systems such as OAuth and LDAP.
• Message queue services (RabbitMQ, Kafka) for asynchronous task processing.
• Cloud services (AWS, Google Cloud) for storage and computing.

For example, in one project, I integrated a payment gateway via REST API, which allowed users to make payments directly from the application.