Couchbase Server vs eXist-db

Couchbase Server has no write-up on Specifiction yet; its figures are above.

eXist-db is a free, open-source NoSQL document database and application platform centered on XML. Its native engine stores textual or binary documents without requiring a database schema, and it is designed for self-hosted deployment on Linux, macOS, or Windows. The product implements XQuery 3.1, though some features and functions are unsupported, and RESTXQ lets developers deploy RESTful services from XQuery annotations. Its interfaces include REST-style HTTP, SOAP, XML-RPC, and WebDAV. A browser-based IDE provides syntax coloring, code completion, and error checking for application artifacts. Full-text search uses an implementation-specific Apache Lucene approach rather than the W3C XQuery and XPath Full Text 3.0 specification. Security extends Unix permissions with access control lists and external authentication realms. The software is licensed under the LGPL for academic, non-commercial, and commercial use. The documentation lists Java 8 for versions 3.x–6.x or Java 21 for version 7.x, about 500 MB of disk space, and at least 512 MB of memory.