https://www.flightradar24.com/
Example on a Sunday at 20 p.m .:
Obviously, this only applies to commercial aircraft that have a transponder (details of the information and identification is available for each aircraft!). It is possible to put filters and there is the trace of the traveled path!
call sign
Altitude
Speed
Radar
aircraft type
Example: put callsign AF if you only want to see Air France planes in flight ...
Really interesting for those who are more or less interested in aviation (and I know there are quite a few here).