We had previously used VIES (the EU's website to check and verify VAT numbers); but have been experiencing service issue problems when trying too access their site. We suspect that this has something to do with Brexit.
We decided to search for an alternative and have found this site vatcheck.eu So far, we haven't had any problems with it and it is very quick and easy to use.
Whereas the VIES site required the user to enter their own VAT number in addition to the VAT number searched for, vatcheck.eu does not require the user to enter their own VAT number or any personal details whatsoever.
We hope that you find it useful.