On: Highcharts – JavaScript charting framework

[dutchbrit]

Chart.js is my current favourite - still doesn't have all the same features as Highcharts but usually sufficient for my needs.

[nilkn → dutchbrit]

It's been a while since I've used it, but I had to abandon Chart.js due to bad support for legacy browsers (even though it claimed the contrary). I haven't used Highcharts, but I've found flot to be pretty solid in cross-browser support.