I have an idea for a new plugin useful for users/companies trying to close a deal faster:

Basically this plugin should track logged in users actions like: clicks on favorite ads and clicks to reveal phone number on ads. Then in Dashboard there should be a table list detailing the user's name (e.g. John Doe), date of action (e.g. 30/06/2020), type of action (e.g. Favorited/Revealed Number) and phone number so he can get contacted and try to negociate a deal. I think this is benefical for buyers because they can get a better deal and for sellers because they can sell faster. I am willing to pay for such plugin around 50euros.

I would say such actions would not be legal

If users get's an Opt-in option on registration form to give their consent (also in Profile) there is no issue at all. In United States this is legal even without consent. In Europe it's legal as long as they give their consent.

@bobyrou
Even US site having EU customers must have opt-in.
This would be problem on existing sites, how to get opt-in from already registered users.

But this would work perfect for new classified websites like mine. Even for existing classified websites - website owners can find solution to encourage users to opt-in for, like explaining the benefits or offering some credits in exchange for opt-in. There is always solution. You can offer this plugin and we, the buyers of plugin, can find how we can market this to our website users.

I think this is a great idea and I am really interested to buy this plugin!!!

This one is great idea and I like it.