OpenLayers makes it easy to put a dynamic map in any web page. It can display map tiles and markers loaded from any source. MetaCarta developed the initial version of OpenLayers and gave it to the public to further the use of geographic information of all kinds. OpenLayers is completely free, Open Source JavaScript, released under a BSD-style License.

OpenLayers is a pure JavaScript library for displaying map data in most modern web browsers, with no server-side dependencies. OpenLayers implements a JavaScript API for building rich web-based geographic applications, similar to the Google Maps and MSN Virtual Earth APIs, with one important difference – OpenLayers is Free Software, developed for and by the Open Source software community.

As a framework, OpenLayers is intended to separate map tools from map data so that all the tools can operate on all the data sources.

Website: http://www.openlayers.org/

Download: http://www.openlayers.org/download/