I am having internet problems and the ISP technicians suggested that something is using my bandwidth.
Is there a software to monitor which processes use how much bandwidth?
Bandwidth Usage on Mac – Monitor Internet Activity via Applications
activity-monitorapplicationsinternetmacos
Best Answer
I believe that Rubbernet is exactly what you are looking for.
The only downside is that Rubbernet cannot distinguish between LAN traffic and WAN traffic. It sounds like you are looking at one computer, so that shouldn't be an issue.
There is a demo available on their website, or you can buy it from the Mac App Store for US$25, which seems to be a pretty good deal since they want € 29.99 (about US$42) for a single user copy or € 49.99 (almost $69) for a "family pack" if you buy through their website.
(Hat tip to Macworld.com for bringing it to my attention a few months ago.)
If you want something cheaper, NetUse Traffic Monitor might suit you too.