There are a number of services that offer user management:<p><a href="https://aws.amazon.com/cognito/" rel="nofollow">https://aws.amazon.com/cognito/</a>
<a href="https://auth0.com/" rel="nofollow">https://auth0.com/</a><p>You just need to provide a hook on the app/website to authenticate.<p>Not sure if you can completely get away from doing any kind of database. I bet you'll need to store some kind of user state. Again, try amazon dynamodb, or their Postgresql alternative, all cloud hosted with backups.<p>Now some comments:<p>- Founders demanding "unhackable" implementation. Be clear, explain you'll do your best to ensure that is the case, but even large companies with 1,000s of developers and security professionals are still getting hacked. Explain there is no way you can provide a guarantee (so that later it does not become reason for dismissal or something like that). And whoever will guarantee unhackable solution is simply lying.<p>- If I understand correctly, there are 2 founders (idea people), and you are the first programmer. If that is the case, you are the sole person responsible for implementation, design, support, hardware, deployment, networking.. and other stuff. And you got 6% of equity... I would question that.<p>Good luck