Chart.js seems to be a good alternative to Google's Chart API and other commercial chart drawing libraries.

• good looking charts Show archive.org snapshot
• canvas based (means less memory consumptive, but no interactivity out of the box)
• highly configurable
• good API and documentation Show archive.org snapshot
• just 4.5 kilobytes
• MIT license
• Browser support: all browsers supporting the canvas element (for IE8 and below, use the polyfill Show archive.org snapshot as describes in the chart.js documentation Show archive.org snapshot )

Rails Long Term Support

Rails LTS provides security patches for old versions of Ruby on Rails (2.3, 3.2, 4.2 and 5.2)

• Prevents you from data breaches and liability risks
• Upgrade at your own pace
• Works with modern Rubies

Read more Show archive.org snapshot

Look at the documentation for general issues and browser support Show archive.org snapshot .