Is it GDPR compliant?

Yes, see the FAQ on GDPR:
https://www.addtoany.com/buttons/faq/#gdpr

I read this: “Our technology vendors are GDPR-compliant, and may temporarily store an IP address and set a client cookie for security purposes.”

Whose IP-Adress will be stored?
How will it be stored? (complete?)

Hey Pat, did you see this significant news just out from the Advocate General for the European Court of Justice (CJEU) about GDPR and social media sharing buttons?

https://www.theregister.co.uk/2018/12/20/eu_facebook_like_button_gdpr/
https://www.courthousenews.com/judge-urges-wide-liability-net-on-facebook-data-collection/
https://www.itpro.co.uk/data-protection/32622/eu-debates-gdpr-joint-liability-ruling-for-websites-using-social-widgets

If the Court rules thusly, then it sounds like the use of the “standard” Facebook Like button on a website with EU traffic could become highly problematic for the website owner.

Question: Do the AddtoAny share/like buttons not pass any data to Facebook et al. by default, but only if clicked upon by the website visitor? Thanks.