Only reads public endpoints (status.php, nodeinfo, capabilities, response headers). Scan servers you are allowed to look at. Results are not stored or shared.
Run it on your own premises
Scan servers inside your network, or keep it next to your Nextcloud, without going through this site.
Nextcloud Peek is open source under the MIT license. Read the source and download it as a small .NET 10 project that brings its own web server, then start it with dotnet run.