HSQLDB

vs

PouchDB

PostgreSQL, or Postgres for short is a widely popular, free and open-source relational database management system. PostgreSQL is available for all major operating systems including macOS, Linux, Windows, BSD and Solaris. The project has been in active development for over 30 years now, and powers many of the applications you use on a daily basis.

The worlds most popular free open-source relational database, MySQL is used by 150,000 + companies across the globe. The relational database management system is released and distributed under the GPL license and openly developed by the community. MySQL uses SQL as its query language and is fully integrated and ACID compliant.

Amazon DynamoDB is a key-value and document database that delivers single-digit millisecond performance at any scale. The database is fully managed, multiregion, multimaster, and durable with built-in security, backup and restore, and in-memory caching for enterprise-scale applications. Amazon DynamoDB is part of Amazon Web Services and integrates well with other cloud-based AWS products.

CouchDB is a free and open-source document-oriented NoSQL database developed by the Apache Foundation. The database is written and implemented in the language Erlang and provides the use of multiple formats and protocols to store, transfer, and process data. With CouchDB you query data with JavaScript using MapReduce, and HTTP for an API. Which can be done across multiple distributed CouchDB instances as the database has the ability to synchronize multiple copies of the same database, across servers.

MongoDB is an open-source document-oriented distributed database built for modern applications. MongoDB uses JSON-like documents with optional schemas and is classified as a NoSQL database. The database is freely distributed under the Server Side Public License, but MongoDB provides commercial version of the database for enterprise-scale applications.

ArangoDB is a database system that was designed to support key/value, document, and graph data to be stored together, and queried via a unified language called AQL. The project is developed by ArangoDB GmbH, and released free and open-source under the Apache License 2.0. The universal "native multi-level" design of the database allows for a flexible approach when structuring and building an application, a feature that many have come to love.