You can use CyberChef to calculate the entropy of a file:
Not just the entropy value for the whole file, but also other options:
Like a curve:
Our an image:
Didier Stevens
Senior handler
Microsoft MVP
blog.DidierStevens.com
(c) SANS Internet Storm Center. https://isc.sans.edu Creative Commons Attribution-Noncommercial 3.0 United States License.
