Is there a limit on the number of requests that an external application can perform with the Dynamics 365 Business Central APIs?
I think that this is actually an undocumented response (please correct me if I’m wrong) but the answer is absolutely yes.
As every well architectured solution, Dynamics 365 Business Central service limits the number of simultaneous calls in a certain sliding window. If you have an external service that performs too much requests on a tenant, you could receive an error like:
"message": "Too many requests reached. Actual (101). Maximum (100)."
This is mainly to avoid things like denial-of-service attacks (DoS) and to avoid problems like lack of resources.
What you should do in your external application to avoid this?
You should handle how you perform requests to a Dynamics 365 Business Central API and if you receive this error you should adopt something like a retry policy on your API calls.
What are the official numbers for these limits on a SaaS environment? I will update this post when I’ll have an official response