What technologies were used in the project instead of Kafka for message processing?

In projects where Kafka was not used for message processing, alternative technologies such as RabbitMQ, ActiveMQ, or Amazon SQS are often employed. These systems provide reliable message delivery and support various exchange models, such as queues and publish-subscribe.

For example, RabbitMQ uses the AMQP protocol and is well-suited for scenarios requiring guaranteed delivery and complex message routing. In some cases, built-in message queues within frameworks, such as Spring Boot with an embedded broker, can be used to simplify architecture.

The choice of an alternative depends on the requirements for system performance, scalability, and reliability.