Watching Instagram stories anonymously is possible because public story data is accessible without a personal login. IG Story Viewer requests that public data directly, plays it in your browser, and never registers a view against your identity. The result: you watch Instagram stories anonymously and the account owner sees nothing unusual on their end.
This works on any device. Whether you are on an iPhone, an Android phone, or a desktop browser, the process is the same — open the page, enter the username, and watch. No app to download, no account to create, and nothing stored after you leave.