Well, my immediate response is “figure out how many clients you would expect to have first”… but if you’re accepting of the staleness (i say 0-10 seconds, it’s probably more like 2-15 seconds, because of the overhead time of your code making the call, writing to the file, etc. but the scale is still roughly the same)…
Again, I come back to the fundamentals of the concept. You told me “this is the data of the call center i work for”, but you dont know how many people are going to visit your data, and you dont know who they are… does your data center WANT you exposing this information? Does the API license you have ALLOW you to do so in a public manner?