According to the (issue tracker of highcharts)[https://github.com/highcharts/highcharts/issues/4405#issuecomment-
125124004] they do not consider the code open source. It's available for reading but that's about it.
The code is provided under CC-BY-NC via github.
See also:
https://shop.highsoft.com/faq#Non-Commercial-0
| Extendable to Custom Charts | ✓ | ✓ | | |
| Supports Modern Browsers | ✓ | ✓ | ✓ | ✓ |
| Extensive Documentation | ✓ | ✓ | ✓ | ✓ |
-| Open Source | ✓ | ✓ | ✓ | ✓ |
+| Open Source | ✓ | ✓ | | ✓ |
Built in Chart Types