Some things that come to mind on a quick reading of the website you linked:

- you can only sign up by using github. This is equally nonsensical as requiring a facebook account to sign up. I have neither. But I have e-mail, so why can't I play along?

- I legitimately cannot tell what platform this is on. Is it a webapp or is it a OSX/mac only local application?

- Does it exist on mobile?

I mean this as constructive criticism and I hope that somebody related to the project/company reads this and improves the information. But from what I can see this application is locked down for those on github and who operate macs. That makes it useless to a whole lot of people.

*edited for formatting