DBSlayer is a middleware that allows web applications to access databases through HTTP and JSON. It provides a simple way to query databases by sending SQL statements in a JSON-formatted HTTP request and receiving the results of the query in the HTTP response also formatted in JSON. It aims to be independent, scalable, flexible and simple. Some features include connection pooling, load balancing queries across multiple databases, and automatic failover to alternate databases. It works by acting as an intermediary between web applications and databases, handling the network communication and database access transparently through its HTTP/JSON interface.