OpenLayers

OpenLayers is an open source (provided under a modified BSD license) JavaScript library for displaying map data in web browsers. It provides an API for building rich web-based geographic applications similar to Google Maps and MSN Virtual Earth. The library includes components from the Rico JavaScript library and the Prototype JavaScript Framework.

OpenLayers is used by OpenStreetMap project for its "Slippy Map" map interface.

Features

 * Load map data from many sources:
 * Web Map Service
 * Web Feature Service
 * Google Maps
 * OpenStreetMap
 * Virtual Earth
 * Yahoo! Maps
 * MapServer
 * MapGuide Open Source
 * GeoServer
 * ka-Map
 * World Wind servers
 * GeoRSS support
 * Easy mouse/keyboard navigation
 * Adding markers
 * Layer selection

History
OpenLayers was created by MetaCarta after the O'Reilly Where 2.0 conference on June 29-30, 2005, and released as open source software before the Where 2.0 conference on June 13-14, 2006, by MetaCarta Labs. MetaCarta maintains an active role in supporting and managing the project. Two other open source mapping tools released by MetaCarta are FeatureServer and TileCache. Since November 2007 OpenLayers is an Open Source Geospatial Foundation project.

Commercial (but free for public use)

 * Google Maps
 * Yahoo Maps
 * Bing Maps
 * Map24

Open Source

 * Mapiator