legec
You can always fall back to MS Paint: https://ms-paint-i.de/
When I mean "give instructions on how to test it" : we created a test subscription on our platform, sent instructions on how to register and see what our app is doing, and our logs showed that no one attempted to go to that test subscription.
We also asked ourselves if we were exchanging emails with a human or a robot, and couldn't reach a conclusion.
[spoiler]
https://joshworth.com/dev/pixelspace/pixelspace_solarsystem....
https://joshworth.com/dev/pixelspace/pixelspace_solarsystem....
https://joshworth.com/dev/pixelspace/pixelspace_solarsystem....
https://joshworth.com/dev/pixelspace/pixelspace_solarsystem....
https://joshworth.com/dev/pixelspace/pixelspace_solarsystem....
https://joshworth.com/dev/pixelspace/pixelspace_solarsystem....
https://joshworth.com/dev/pixelspace/pixelspace_solarsystem....
https://joshworth.com/dev/pixelspace/pixelspace_solarsystem....
https://joshworth.com/dev/pixelspace/pixelspace_solarsystem....
https://joshworth.com/dev/pixelspace/pixelspace_solarsystem....
[/spoiler]
(note : I mean the comments on StackOverflow, not the comments here in Hacker News ... )
One use case is : "when did branchA fork from master ?"
git log --graph --oneline --... --first-parent branchA master