The newer (4.8+) Impact Account system separates enabling premium and listing info (such as capes). It also adds a layer of privacy to showing info.
Our API shows a SHA hashed version of your Minecraft ID, which prevents somebody from easily getting a list of Impact Account holders. However, it is still possible for them to check if individual Minecraft accounts have Impact Account features. They can do this by hashing the Minecraft ID and then looking through the API's list to see if the resultant hash is in the list. If you don't want this to be possible, you can enable Incognito Mode and you won't be included in the list. Not being in the list means no one can tell if you have an Impact Account or not, including other Impact users.
Because listing info and enabling premium now separated, if you enable Incognito Mode you will still get access to other Impact Account features, such as donation perks like Ignite and nightly builds. These features use Minecraft's authentication system (the same one used by Multiplayer Servers). This means you must launch Impact while online and logged in to the Minecraft account that is linked to your Impact Account.
The legacy (pre 4.8) Impact Account system uses plain text lists that list all Minecraft IDs with a given "role" (e.g. the
premium role for donators).
The problem with this is that anyone can easily get a list of Impact Accounts holders. For example an overzealous moderator might set up a system that bans anyone with an Impact Account automatically.
An additional issue is that the same list is used for enabling all features, from capes to Ignite, so it's not possible to have an "Incognito Mode" that doesn't disable everything. Luckily there's little reason to use an Impact version before 4.8, since 4.8 supports 1.12.2, 1.13.2 and 1.14.4. Therefore we don't recommend having "Legacy mode" enabled unless you understand the privacy concerns and want Impact Account features on Impact versions prior to 4.8.
This website and all the code that makes it run, including the Impact Account code, is open source. If you know how to read code why not browse our GitHub repo?
Even better if you spot something that could be improved, you can report an Issue or even contribute directly by proposing a Pull Request!