dhtmlxAccordion integrates easily with other components in the DHTMLX product line. It can be easily integrated into application built with dhtmlxLayout. You can also put other DHTMLX components into the accordion panels with just a single script command. Any item in dhtmlxAccordion can be undocked - extracted from the single layout in order to be displayed separately (in a window of the dhtmlxWindows system).
You can use dhtmlxAccordion for free under GNU General Public License v2, or Free License that allows you to use the component in a non-GPL application/website.
Open Source - GPL v2 - Allows you to use dhtmlxAccordion in open source, GPL-ed projects for free.
Free License - Allows you to use dhtmlxAccordion in non-GPL, proprietary projects (applications) at no charge.