Firebird.NET

The .NET Data provider is written in C# and provides a high-performance, native implementation of the Firebird API

Couchbase

Official Couchbase .NET client library, based on the Enyim memcached client

Cassandra

DataStax .NET driver for Apache Cassandra

StackExchange Redis

General purpose Redis client from StackExchange

ServiceStack Redis

.NET's leading C# Redis client

RethinkDb.Driver

A RethinkDB database driver in C# striving for 100% ReQL API compatibility and completeness.

MongoDB

Official MongoDB C# driver

Npgsql

.NET data provider for PostgreSQL

MySQL Connector

Connector/Net is a fully-managed ADO.NET driver for MySQL

DuckDB.NET

.NET data provider for DuckDB