Azure Cosmos DB Alternatives

OrientDB is an open-source NoSQL database management system written in Java. The multi-model database supports graph, document, key/value, and object models, where relationships are managed as in graph databases with direct connections between records. The database is extremly efficient and can store over 220,000 records per second on common hardware, and traverse thousands of records in milisecons. OrientDB scales well on multiple machines, thanks to the multi-master replication where there is no single bottleneck on writes like with master-slave replication.

LevelDB is a free and open-source key-value storage library developed by Google. LevelDB provides on-disk storage and ordered mapping of string keys to string values. With LevelDB data is stored and sorted by key, and the keys and values are arbitrary byte arrays. The library will also automatically compress files using the Snappy compression library to optimize for storage capacity.

KeyDB is fast, free, and open-source NoSQL database with full compatibility for Redis APIs, clients, and modules. The database was originally forked from the Redis code-base and has been improved to handle multithreading, memory efficiency, and higher throughput. KeyDB is now a fully multithreaded and allow many machine cores to operate a single node resulting in 5X the throughput of Redis (v5) and up to 3x the throughput of Redis (v6). KeyDB also includes Redis Enterprise such as Active Replication, FLASH storage support, and other features like direct backup to AWS S3.

Cockroach is a distributed key/value datastore that allow you to build, scale and manage modern, data-intensive applications. The database delivers distributed SQL by combining the familiarity of relational data with limitless, elastic cloud scale and bulletproof resilience. Correct data is a must for mission-critical and even the most common applications. CockroachDB provides guaranteed ACID compliant transactions, allowing you to fully trust your data.

Neo4j is a commercially provided graph database management system developed by Neo4j, Inc. The graph database is fundamentally different to the relational model found in relational database management systems (RDBMS). With Neo4j, each data record, or node, stores direct pointers to all the nodes it's connected to. The database is also designed to perform complex queries with complex connections orders of magnitude faster. Neo4j is ACID-compliant and suited for projects that requires complicated relationship structures.

TerminusDB is an open-source full-featured in-memory graph database management system that stores data like git.

BigchainDB allows developers and enterprise to deploy blockchain proof-of-concepts, platforms and applications with a blockchain database, supporting a wide range of industries and use cases. BigchainDB provides high throughput, low latency, powerful query functionality, decentralized control, immutable data storage and built-in asset support, BigchainDB is like a database with blockchain characteristics.

GraphDB is a simple graph API for SQL Server. The GraphDB database resides inside of your SQL server and together with .Net 4.5 assemblies partitioned into a client and an admin API. The Client API allow users to connect to a GraphDB store and store graphs of entities in workspaces. The API has a rich set of data-, security- and graph-related methods to easily manage entities, collaboration and networks. While the Admin APU allows you store and manage data, and manage security related tasks and user accounts.

TaffyDB is a free and open source, Pure-JavaScript database abstraction that stores data in JSON format. TaffyDB provides INSERT, DELETE, GET (SELECT)  and JOIN methods to execure the data similar to that of traditional relational SQL databases. TaffyDB allows you to quickly setup an in-memory database that can be used in the same fashion as an SQLite database would, without configuration and a database server running.

NosDB is an open-source NoSQL Database that is 100% native to .NET. The database is released under the Apache 2.0 License and can be used in commercial and non-commercial projects alike. NosDB helps you accelerate your.NET development by providing a flexible JSON schema. Developers use NosDB to build projects tailored around Personalization, Content Management, Catalogs, Data Logs, Real-Time Big Data, Internet of Things, Scalable Web Apps, Scalable Web Services and more

CrateDB is the leading, distributed SQL database for relational and time‑series data. CrateDB provides a distributed SQL DBMS built atop NoSQL storage & indexing delivers the best of SQL & NoSQL in one DB. It's designed for simple scalability with a masterless architecture with auto-sharding & replication. It also provides solutions for dynamic schema where the schema evolves automatically as new columns are inserted, while handling any tabular or non-tabular data to support a wide range of use cases. CrateDB is the perfect choice for your machine data.

DeepDB also known as DeepSQL is a proprietary MySQL storage engine designed for OLAP and OLTP workloads. It was designed to be an alternative to the InnoDB storage engine for MySQL.