In which non-relational databases have you had experience working?

The following systems are often used when working with non-relational databases:

• MongoDB — a document-oriented database, well-suited for storing JSON-like documents.
• Redis — an in-memory key-value store, often used for caching and fast operations.
• Cassandra — a distributed columnar database, suitable for processing large volumes of data with high availability.
• Elasticsearch — a search engine based on Lucene, used for full-text search and analytics.

Work experience typically includes setup, query optimization, ensuring fault tolerance and scalability, as well as integration with applications and monitoring systems.