Alternatives to JanusGraph

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.

RedisGraph is the first free and open source queryable Property Graph database to use sparse matrices to represent the adjacency matrix in graphs and linear algebra to query the graph.

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.

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.

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.

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.

RethinkDB is a scalable, open-source database designed for real-time applications. When your app polls your database for data, it becomes slow, unscalable, and cumbersome to maintain. RethinkDB solves this by providing a new database access model, where developers can instruct the database to continuously push updated query results to their applications, without polling.

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.

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.

Redis is a free and open-source, in in-memory data structure store that can be used as a database, cache or message broker. The project is community developed and released under the BSD license. Redis supports common data structures including strings, hashes, lists, sets, sorted sets with range queries, bitmaps, hyperloglogs, geospatial indexes with radius queries and streams.

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

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.

Azure Cosmos DB is a non-relational NoSQL database trusted by leading enterprises globally. With Azure Cosmos DB you can run No-ETL analytics over real-time operational data and run near-real time analytics and AI on the operational data within your NoSQL database, to reduce time to insight.

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.

A Chinese developed open-source NewSQL database that supports analytical processing and hybrid transactional workloads. TiDB is licensed under the Apache 2.0 license and primarily developed by PingCAP, Inc. The database provides high availability with strong consistency and horizontal scaling and is compatible with MySQL.

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.

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.