Does it work for sole traders and one-person businesses?

VIES validates VAT numbers regardless of the legal form behind them — a VAT-registered sole trader's number validates the same way a company's does. One caveat that applies to both: VIES only shows numbers a member state has enabled for intra-EU transactions, so a purely domestic VAT registration may not appear. Whether a name and address come back depends on that country's data policy, not the business type.