If you want domain names in other languages, you could spend a bundle on translations. You could also get some copywriting done in several versions, and then a/

If you want domain names in other languages, you could spend a bundle on translations. You could also get some copywriting done in several versions, and then a/b test with them. You could talk to a patent lawyer and try to get some of your tech patented (file provisionals at this point), file trademarks both nationally and internationally, ... and spend some money on design. If you learned to code by yourself, did you design it too? I have been amazed at what a good designer has done when they have remade some of my creations. But mostly I agree with customer acquisition. That is the best place to put your extra cash.