But aren't you risking to get sued by doing that? I think almost all job contracts include a clause stating that any paid work outside the company is allowed w

But aren't you risking to get sued by doing that? I think almost all job contracts include a clause stating that any paid work outside the company is allowed with written permission only (or, worse, everything produced belongs to the company). I don't think any employer would support that. Of course, starting a start up is not exactly 'paid' work in a casual way, but I my common sense says that it's quite clearly 'paid work', or at least intended to be paid.