CosmosDB, Microsoft's NoSQL database offering for Azure, has evolved from its previous identity as DocumentDB by incorporating a broad range of features, including document, columnar, key-value, and graph database capabilities. It aims to serve numerous database needs through a universal abstraction model called atom-record-sequence (ARS) and supports multiple APIs such as SQL, MongoDB, and Cassandra; however, this versatility might limit its feature set and performance. A key challenge is the management of Request Units (RUs), which can lead to unpredictable costs and necessitate expert management to optimize performance. In contrast, Couchbase Capella offers a more predictable pricing model with flexible scaling options, memory-first architecture, and comprehensive SQL support, which can result in significant cost savings and performance improvements, as evidenced by Facet Digital's switch from CosmosDB. While CosmosDB offers attractive features like global data distribution and multiple consistency models, its complicated pricing structure and performance limitations, particularly in sharding and indexing, may make it less suitable for large-scale, mission-critical applications compared to Couchbase Capella.