The Blazemeter performance reports show, each on their own way, representations of the metrics of the executed test. But the need may arise to use the raw data that the reports are based on, e.g. to use them into another tool in order to get different graphical representations. How to get hold of these raw data?
The raw data are contained within the kpi.jtl which is located in artifacts.zip of each engine.
So, if you want the raw data for the entire test, you need to go to the logs tab of the test, select each engine one by one, download its artifacts.zip and extract the kpi.jtl. When you concatenate all kpi.jtl files, you have your raw data.
Make sure to get rid of the header line for all files except the first one, before concatenating them. The result is a csv file with raw data of the entire test.