Recently, charte.ca feature set got new additions: chart cloning and chart sharing. Cloning is getting an exact copy of a source chart. Sharing is allowing other users to edit your chart.
Consider an example: Bob is working on a chart and wants Alice to help him. Bob opens the chart in the editor, finds "Sharing" panel and clicks "Share with another user" button. He is presented with a popup that displays a URL of the invitation that Bob has to send Alice so she gets access to his chart. Bob presses "Confirm":
Now, "Sharing" panel displays the invitation in the list. If Bob changes his mind, he can cancel this invitation by clicking the "x" button on the right of the invitation: