Which tool to upload bulk images to multiple posts?

I have to upload bulk images to thousands of posts of multiple pbns.
I already have some free photos, now I wonder how to easily upload them to each wp website, randomly.
One option can be to use the plugin Quick Featured Images, I was reading that maybe it can do it, but I never tried it. I already have the Festinger cracked version , but before spend time on it I wonder if anyone has already found a solution for this job.

Any suggestion?

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