I would like to work for a startup but only for a couple of months

I love the startup pace and the possibilities of the early days, however I want to work on my own projects and ideas. Does one excludes the other?

How would you feel if I, as an applicant to your startup, tell you that I want to work with you but just for a couple of months (max. 4 months)?

Not a chance at our 3-yr old startup. That's less than a summer project, and nobody expects much from summer interns. Maybe you haven't written highly async Go services in containers orchestrated by kubernetes. You would spent those two months just ramping up on our code base and customer issues just to be productive. And if by some miracle you actually produced production code, nobody wants the author of that code to immediately walk out the door. Experienced programmers understand that 80% of the cost is in the maintenance over the lifetime of the code. That is a lot easier to do if the author is still around.

It depends on your seniority and speciality. It takes quite a while to warm new team members into real productivity on mainline technical labor. Often, the first month or two of a new hire has a negative impact on total team efficiency. It's a similar principle to why you can't just staff up at the last minute before a deadline.

The exception is if you're an expert in some specialty that's relevant and underserved on the team. In that case, the relationship becomes more of a consulting role, where you do a very specific thing very effectively and in a way that it can be smoothly handed off to long-term maintainers.

Another opportunity is direct contracting for very early stage entrepreneurs. Building the prototypes or MVP's that help them understand and articulate their ideas. Even then, four months can be pretty narrow window in the real world and there's often a bias for people who'll stick around for the next phase.

One final possibility -- and the least reliant on other people's accommodation -- would be for you to just expand the period of your cycle. Can you commit 12-18 months at a time? That's actually pretty normal in the startup world, and if you manage your finances well, it can set you up for an equally long stint of solo work.

From the perspective of a startup you would cause too much expense. They have to pay your onboarding and until you produce real value 1-2 months will pass. In this time they already have to pay you. If you leave the company after 2 further months their expense for you will be higher than your earnings if you are not highly specialized and more a consultant than an employee.

However: In Germany most companies have a time of probation for 3-6 months. In this time you can leave the company whenever you want. So you could simply join the company and leave it after 4 months.

You may want to look into consulting, specifically around rapid prototyping for non-technical founders if you’re looking to work with early stage startups but want short term engagements. There is a market for it.