Datomic is described as 'database of flexible, time-based facts, supporting queries and joins, with elastic scalability, and ACID transactions' and is an app in the Development category. There are more than 25 alternatives to Datomic for a variety of platforms, including Linux, Windows, Mac, Online / Web-based and BSD. The best alternative is MongoDB, which is free. Other great apps like Datomic are Microsoft SQL Server (Freemium), Apache Cassandra (Free, Open Source), RethinkDB (Free, Open Source) and CockroachDB (Free).
MongoDB is a document database with the scalability and flexibility that you want with the querying and indexing that you need MongoDB stores data in flexible, JSON-like documents, meaning fields can vary from document to document and data structure can be changed over...
SQL Server delivers on Microsoft’s Data Platform vision by helping your organization manage your data by enabling you to store data from structured, semi-structured, and unstructured documents within the database.
Apache Cassandra has become the leading NoSQL platform driving many of today's modern business applications by offering continuous availability, high scalability and performance, strong security, and operational simplicity while lowering the overall cost of ownership.
RethinkDB pushes JSON to your apps in realtime. When your app polls for data, it becomes slow, unscalable, and cumbersome to maintain. RethinkDB is the open-source, scalable database that makes building realtime apps dramatically easier.
Cockroach is a distributed key/value datastore which supports ACID transactional semantics and versioned values as first-class features. The primary design goal is global consistency and survivability, hence the name.
DB2 offers industry leading performance, scale, and reliability on your choice of platform from Linux to z/OS. DB2 supports storing XML and relational data and offers SQL PL and PL/SQL procedural languages.