Uri from Overwolf emailed me earlier this year to ask my thoughts on whether we'd be okay with a potential third-party program. I replied with

"Generally we ban users who run programs that interact with the game client directly (overlays, etc). They're allowed to run/create third party programs that can operate without the game client running, for example ones that process logs from the hard drive. It sounds to me like what is being proposed here would not be allowed, unfortunately."

He replied clarifying some features of the program. My reply was:

I figured it'd be useful to explain some key reasons why we don't encourage people to download external tools:

• Downloaded tools run on the user's machine and can steal Path of Exile passwords or install malware. While I understand that your tool probably doesn't do this, there's nothing to stop that being the case (for example if your build machines were compromised). We cannot encourage a user to run a program developed by a third party due to this risk.
• If a tool is useful and provides gameplay benefit, then competitive players have to use that tool. If that involves installing a program on their computer and being exposed to the above risk, then users have to pick between being at a competitive disadvantage and exposing their account details (or worse).
• While many downloaded tools don't break the rules regarding automation of the game client, sometimes the developers push the limit and start to sneak features in that are over the line. That's why we require that the tool is fully functional if the game client were not running (i.e. it doesn't need the game client open in order to work).
• It's often more efficient for a web-based tool to interact with our APIs because then it can cache results across multiple users and is easier for us to rate-limit successfully. Tools running across many users' home machines may request the same data as each other and are hard to slow down if the site is overloaded (which it often is due to these tools).

Later in the conversation after more explanation from him, I said "This all sounds good, though the reasons I mentioned in my mail are why we have issues promoting third-party apps. We don't disallow their use though unless they interact with the game client itself."

So as long as this app can function entirely without the game client open, it probably follows the above rules and would not result in players being banned for using it. I haven't checked out what it does and am not going to have time until after the launch of Harvest. There is zero chance that I would personally install third-party software like this on my computer to help with playing a game.