FerretDB is described as '(formerly MangoDB) is an open-source proxy, which converts MongoDB wire protocol queries to SQL, and uses PostgreSQL as a database engine' and is an app in the development category. There are more than 100 alternatives to FerretDB for a variety of platforms, including Linux, Windows, Mac, Self-Hosted and Web-based apps. The best FerretDB alternative is SQLite, which is both free and Open Source. Other great apps like FerretDB are PostgreSQL, MySQL Community Edition, MongoDB and MariaDB.
Vertica is a grid-based, column-oriented database designed to manage large, fast-growing volumes of data and provide very fast query performance when used for data warehouses and other query-intensive applications.
LiteDB is an open-source, MongoDB-like database that requires no configuration and is mobile-ready. It's a serverless database delivered in a single DLL under 450kb, fully written in .NET C# managed code and compatible with .NET 4.5 and NETStandard 2.0.
Brazil
NosDB is a 100% native .NET Open Source NoSQL Database (released under the Apache 2.0 License). NosDB is extremely fast and linearly scalable and allows your .NET applications to handle extreme transaction loads (XTP).
United States
OrbitDB is a serverless, distributed, peer-to-peer database. OrbitDB uses IPFS as its data storage and IPFS Pubsub to automatically sync databases with peers. It's an eventually consistent database that uses CRDTs for conflict-free database merges making OrbitDB an excellent...
A Postgres Database as a Service platform so you can focus on writing your app, not on becoming a database administrator.
Fauna is a flexible, developer-friendly, transactional database delivered to you as a secure, web-native API.
The GridGain In-Memory Data Fabric is a proven software solution, which enables high-performance transactions, real-time streaming and fast analytics in a single, comprehensive data access and processing layer.
United States
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.
EJDB 2.0 — Embeddable JSON Database engine C library. Simple XPath like query language (JQL). Websockets / Android / iOS / React Native / Flutter / Java / Dart / Node.js bindings.
Estonia
EU
Datomic is a database of flexible, time-based facts, supporting queries and joins, with elastic scalability, and ACID transactions.
Austria
