Every dynamic application needs some form of database to store its data logically and sorted. However, there is no one-size-fits-all solution, but it should always be looked at the use case to make the right choice. We have experience in all common databases and use them productively.
As the best-known document-based database, MongoDB is a good all-rounder solution for all projects. Data is stored here as a JSON structure, which is why it is called a document. Correlations of 1-to-1, 1-to-N or N-to-N are possible as with relational databases via references to the document ID. Due to the JSON format, developers quickly find their way around. Since there is no fixed data schema, the data structure can be changed at any time, which is not always desired.
MySQL is one of the most widespread relational database management systems in the industry and offers very good performance. As Open Source software, MySQL is available for various operating systems and forms the basis for many dynamic web presences.
PostgresSQL, short Postgres, describes itself as "the most advanced open-source relational database in the world". It has nearly identical performance to MySQL and offers additional features that give it advantages over MySQL. This comes from the fact that Postgres is an object-relational database, while MySQL is purely relational.
Usually used as a fast cache memory, Redis supports numerous apps to deliver additional performance. Data is kept in-memory instead of on the hard disk to achieve much faster read and write speeds. Due to this nature, a Redis database is not for persisting data, but perfect for caches.