After a quick browse of the Tax Jar website I got the solid impression that they were US only. I saw mention of 'sales tax' but nothing about VAT, GST, HST, etc. No mention of international or shipping. And their pricing page which I normally find to be useful for this type of thing was actually totally confusing to me.

The one thing on the pricing page that jumped out at me was, "AI-driven product taxability recommendations"

AI recommendations and dealing with the tax authorities doesn't really seem like a sound choice.