VoltDB Alternatives for Self-Hosted

PouchDB is a free and open-source JavaScript database inspired by Apache CouchDB. The database is designed from the ground-up to run well within modern web browsers. With PouchDB you can create web applications that works as well offline as they do online. PouchDB achives this by storing data locally, then synchronize it with CouchDB and compatible servers when the user get internet access once again. This is especially useful for applications facing countries and regions with lower quality internet connections or unstable infrastructure.

SQLite is a free and open-source relational database management system that implements a small, fast, self-contained, high-reliability, full-featured, SQL database engine. Rather than being a typical client–server database engine, SQLite is self-contained and can be embedded into applications. Making it perfect for development frameworks that want to provide a default database without setup, or applications that needs an embedded database. SQLite is built into all mobile operating systems and most computers and comes bundled with a countless applications. SQLite is also ACID-compliant and implements most of the SQL standard, generally following PostgreSQL syntax.

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.

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.

QuestDB is a relational column-oriented time series database designed for real-time analytics on time series and event data. It uses the SQL language and include extensions for time series data. QuestDB is released as free and open source software and distributed as a single binary including a trimmed version of the JVM (Java Virtual Machine) weighing in at only 24.5 MB.

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.

MonetDB is an column-oriented database management system developed at the Centrum Wiskunde & Informatica. The database is released as free and open source software under the Mozilla Public License 2.0. By design, MonetDB can handle high performance on complex queries against large databases with hundreds of columns and millions of rows.

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.

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.

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

TimescaleDB is a leading open-source relational database for time-series data. The database is provided as fully managed or self‑hosted software, giving the power of choice back to developers and organizations. Timescale gives you all the reliability and flexibility of PostgreSQL. It allows you to use regular SQL to construct queries to better understand your products and your users. While achieve 10-100x faster queries than PostgreSQL, InfluxDB, and MongoDB with native optimizations for time-series.

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.