Freeware - Bertom Audio EQ Curve Analyzer VST Plugin

https://www.bertomaudio.com/eq-curve-analyzer.html

EQ Curve Analyzer is an analyzer and signal generator plugin to see the frequency response (magnitude and phase) of any plugin or hardware. Insert the plugin you want to analyse between two instances of EQ Curve Analyzer, the first one set as a signal generator and the second one as an analyzer. Then adjust the latency if needed. That's it! It is particularly useful as a learning tool to see what classic EQs emulations are doing for example. It also features a "group" system that allows you to compare two analyses in real-time on the same graph.