I think the sites and their estimates are pretty impressive considering they contain virtually every home in America, often with interior pics, but they are what they are: free tools that used automated formulas to predict something that can often be a bit unpredictable and can't fully account for the human emotional factor (for example I bet something like the Brady Bunch house zestimated far less than than its actual value)

Some genius is selling wholesalers spam tools.

I don't spend much time on the forum any more....when I stopped it had become a big "bash VRBO" frenzy and I got tired of people using Homeaway's (VRBO's) forum to bash the company that created it.Not to mention that I was one of the people involved with the creation of that forum and hated to see it deteriorate from a place where people could come together to share ideas, help each other and communicate directly with the staff at HA/VRBO to the negative space it had become.But, their tools are still helpful!

Looks like you are.Next, start assembling tools and practicing assessing deals for whatever strategy you're going for.

Their website is really well-designed and has some great tools like calculators.

Unless you already have a plateful, have a big pot of money to invest or are going to knock on doors I think it seems you can do both with reasonable success using available tools.

@Iliya Muzychuk Check out https://www.citybldr.com/ they have built a tool that sounds similar to what you have been working on. they work with homeowners to put together assemblages as well as developers to find suitable sites for projects. 

I am guessing where the money is stored needs to be easily liquidated in short order and not at risk of dropping in value.

A HELOC is a flexible tool. 

They are a necessary tool that you sometimes have to utilize.