About HTTP status codes
When a browser or app asks a server for something, the server answers with a three-digit status code. The first digit tells you the group: 1xx is information, 2xx means success, 3xx is a redirect, 4xx is a client (request) error, and 5xx is a server error.
Type a number or a word to filter the list, or tap a group to browse it. Each entry shows the official name, what it means and the usual reason you would see it.
Is anything uploaded? No. The whole reference is built into the page and runs in your browser.