At Vquence, until now we have used the Thumbstacks chart library for our graphs. TSChartlib is a simple open source charting library that uses the HTML canvas and an IE hack to create its graphs.
Vquence is now getting real serious with charts and graphs and we were thus looking for a more visually compelling and more flexible alternative. If you do a google search for “online charting library“, you get a massive amount of links to proprietary systems (admittedly, some of them offer the source code if you pay a premium). I will not be listing them here – go find them for yourself. However, the world of decent open source charting libraries is relatively small, so I want to share the outcome of my search.
There is the Open Flash Chart libary, which provides charting functionality for flash or flex programmers. The charts look rather nice and have overlays on the data points, which is something I missed thoroughly from TSChartlib.
Then there is JFreeChart, a 100% Java chart library that makes it easy for developers to display professional quality charts in their applications. Another Java charting library is JOpenChart. Incidentally, there’s a whole swag of further Java libraries that do charts and graphing. However, we are not too keen on Java for Web technologies.
Outside our area of interest, there are also open source chart libraries in C#, but C#/.NET is not a platform we intend to support, so these were out of the question.
Our choice came down to the “Open Flash Chart” library vs “Plotkit”. Of the two, the Flash library and technology seems more mature, easier to use, and creates sexier charts. Also, we can sensibly expect all Vquence users to have Flash installed, while we cannot expect the same to be true for SVG. However, I was fascinated by the flexible use of SVG and HTML Canvas and will certainly get back to it later, when I expect it to have matured a bit more.
Our choice of the Open Flash Chart was further facilitated by a rails plugin for it. Score!
Of course: I might have totally missed some obvious or better alternatives. So, leave me a reply if you think I did!