This is similar to login options on many websites and apps where you can sign in using an existing account from another service instead of creating a new account and password.

Developers interested in integrating “Sign in with NoOnes” into their own websites or applications can find the API documentation here
This page allows you to review and manage those permissions at any time.
Note: If you notice an app or website in the list that you do not recognize, do not remember authorizing, or find suspicious, we strongly recommend removing its access immediately and contacting our Support team.On the Connected Apps & Websites page, you can see a complete list of apps and websites that are currently connected to your NoOnes account.
For each connected app or website, you can:
Each connected app or website includes a Details button.
By clicking Details, you can view the permissions that were requested and approved during authorization.
Depending on the app, permissions may include access to:
Always review permissions carefully before authorizing third-party apps.
If you no longer want an app or website to access your NoOnes account, you can remove it at any time.
To remove access:
Once removed, the app will no longer be able to access new information or perform actions through your NoOnes account.

To help keep your account secure: