Self-cert mortgages were effectively banned with the introduction of MMR, however the lender is sidestepping regulation by selling products from the Czech Republic.
Selfcert.co.uk says it can lend up to £500,000 at 85% LTV, with tracker rates starting from 2% above base rate.
However a message on its website today said:
"Due to demand we are having a few issues with our new site at the moment. The site will be live today, Wednesday 20th of January.
"We do apologise but we won't be able to satisfy demand for the vast majority of those that have already contacted us. We are very very sorry but if you haven't already emailed or called us, we won't be able to provide any assistance this time. We are working with others to try and increase capacity.
"We've had over 4,000 people contact us in the first two days and register an interest with us. We are working through these and will contact all of these people within the next 72 hours."