For JavaScript and AJAX applications, Taffy DB is a beautiful tool.

Taffy DB is an open source JavaScript library that acts as a data layer inside the applications. Just think of it as a SQL database in your web browser.

JavaScript Database Library

Let’s say you have a collection of products and you want to find every product that costs less than $10 and is not a book. Simple, just write some JavaScript:
products.find({price:{lessthan:10},
type:{not:"Book"}});

Major features:

  • Under 10K!
  • Simple, JavaScript Centric Syntax
  • Fast
  • Easy to include in any web application
  • Compatible with major Ajax libraries: YUI, JQuery, Dojo, Prototype, EXT, etc
  • CRUD Interface (Create, Read, Update, Delete)
  • Sorting
  • Looping
  • Advanced Queries

Check out the Getting Started Guide for Taffy DB’s capabilities.