dygraphs is an open source JavaScript library that produces produces interactive, zoomable charts of time series. It is designed to display dense data sets and enable users to explore and interpret them. You can mouse over to highlight individual values. Click and drag to zoom. Double-click to zoom back out. Change the number and hit enter to adjust the averaging period.

Another significant feature of the dygraphs library is the ability to display error bars around data series. dygraphs is purely client-side JavaScript. It does not send your data to any servers – the data is processed entirely in the client’s browser.

Requirements: JavaScript Enabled
Demo: http://www.danvk.org/dygraphs/
License: License Free