Make detailed pricing information publicly available (without registering and logging in)
updown.io is STUPENDOUSLY inexpensive compared to most other uptime monitoring solutions available today. This is obviously one of your strongest selling points.
So, "hiding" detailed pricing information on the logged-in-users-only page https://updown.io/credits/buy seems counter-productive. I was especially surprised by the big discounts given when buying credits in bulk. It seems to me that a version of this page (or equivalent information) should be made available for everyone, even if they haven't signed up for the service yet or are currently logged out. (This would make it easier for fans to share this information with friends or other prospective users, as well. Yay virality?)
The pricing widget at https://updown.io/#pricing only gives a very rough idea of the cost. I think a link to a public detailed pricing information page should be added to it and would greatly help with marketing. I certainly didn't realize how crazy inexpensive updown.io really was before I signed up and checked the "buy credits" page.
Now you may think, "but prospective users can just sign up since it's free", but you have to realize that many people are not that eager to sign up to new services just to evaluate them. You are nominally competing with dozens of uptime monitoring services out there, despite the fact that almost all of them are crap and/or hilariously expensive.
For instance, I had initially passed over your service and ended up with Uptime Robot (which honestly is not too great). If someone hadn't "randomly" mentioned your service when I experienced reliability problems with Uptime Robot, I might not even be here...
There's also a bit of a transparency component to this. Right now your service SAYS it's inexpensive, and it's true, but a public detailed pricing information page would PROVE it, which is much better.
(Sorry for the slightly long-winded suggestion, I have neither the time nor energies to write a shorter one...)