Free tax-threshold check
Pick a country or state, say how much you have sold there, and see whether you are near a tax registration. No signup and nothing stored: everything runs in your browser, and an uploaded file is never sent anywhere.
Where is your business established?
The EU's €10,000 and the UK's £90,000 belong to businesses based there. Sellers outside owe registration from the first sale.
What do you sell?
Around twenty US states do not tax software, but most still count those sales toward registration.
Pick a country to start the check
The same sales figure means different things depending on where you are established. A German seller has EUR 10,000 of EU headroom; a seller outside the EU has none and owes registration on the first sale. We would rather ask than guess in the direction that hides an obligation.