They probably consider it either old fashioned or black magic to just write a program to connect to a TCP socket and store the data to disk.
If you have
netcat, it'd be just one command:
netcat -d hostname-or-address port > file.
You can even do it in Bash:
bash -c 'cat < /dev/tcp/hostname-or-address/port > file'. It internally detects paths like
/dev/tcp/ and uses a socket instead, and thus works in Windows also (in WSL, and Cygwin bash).
And if they were a proper web dev, it would have been only a dozen lines of Bash or so to create a minimal WebSocket proxy to handle the HTTP handshake and then just pump the raw data from the specified TCP port directly to the user JavaScript and do the entire UI and processing in a browser. To optimize it a bit, instead of
cat one could use e.g.
dd with
bs=1500 (a typical TCP packet payload size).
I think it was just the typical highschooler they had hired to do the
prototype beta version they intended to initially ship to customers.