While the dynamic and interactive Google Charts are actively maintained, we officially deprecated the static Google Image Charts way back in 2012. This gives us the right to turn it off without notice, which may happen soon.
About the Image Charts API
This service allows you to create dynamic charts using nothing more than a URL string. To see it in action, just paste this URL into your browser's address bar: https://chart.googleapis.com/chart?cht=p3&chd=t:60,40&chs=250x100&chl=Hello|World. Now try changing the text from "World" to your name.
Documented all chart types on separate pages
Added a new page listing all chart parameters
Chart playground added
Some terminology changes:
Financial markers are now called candlestick markers
Text encoding is now called basic text format
Data sets are now called data series
New formula images added
New chart URLs supported ([0-9].chart.googleapis.com)