Ontoprank Reviews 

Avoid this service.

It presents itself as a community for indie developers, but in practice it encourages developers to exchange installs and reviews through a credit system. That is not organic feedback; it is review manipulation.

The fact that they also send unsolicited promotional emails to developer addresses makes it even worse.

I would not risk my App Store or Google Play developer account for something like this.

I received an unsolicited email about this platform, sent to the developer
address on my Google Play listing. It was written as a friendly note from one
indie developer to another: try each other's apps, share honest feedback,
nothing is being sold.

The website tells a different story. It is a credit system. You install and
review other developers' apps to earn points, then spend those points so that
other people install and review your app. Points can also be topped up with
money. That is not feedback between developers. That is ratings in exchange for
something of value.

Both stores prohibit exactly this. Google Play's policy bans incentivized
ratings, reviews and installs, and counts money, goods or anything of equivalent
value as an incentive. Apple removes developers who inflate ratings with paid or
incentivized feedback. The penalty is not a deleted review, it is your app or
your entire developer account.

The site also names no company, no address and no legal representative, only a
privacy page and terms. If your account gets terminated, there is nobody to hold
responsible.

The friendly wording is what makes this risky. It is aimed at solo developers
who are struggling to get their first reviews, and it hides a policy violation
behind the word "feedback". If you get this email, delete it.