We are using Lightning and trying to find out if there is a way to see a breakdown of API usage by source. I have heard of a report that can be used, but it doesn't show up in the Administrative Reports area as other threads have mentioned. All I can see is the total used against our limit on the "Company Information" page, but I'm trying to understand and drill down into usage by source.
Does anyone know of a way to do this?
Are you the Admin? This report type won’t show automatically for other profiles. Also, for me it was only available in Classic.
Switch to Classic and give it a try.
If you want to go further than the OOTB report as mentioned by @Rodrigo, you can use the add-on feature ($$) Event Monitoring with the included Event Monitoring app.
This allows you to see API usage by REST URL as the OOTB report won't tell you which specific API call was made by a given running user; just the counts of all API calls per running user per day
Here's an example dashboard:
