Also in Europe, but I’ve worked at 3 different startups before becoming a contractor earlier this year.

• First one I worked for 5,5 years, joined at ~30 people and saw things grow to 180 people at which point the company was sold and I left about a year after that.
• Second one I worked for 7 years, was one of the first employees and responsible for building their frontend stack as well as various microservices from the ground up. Company grew to about 80 people, but I left after Covid layoffs. I wasn’t one of the layoffs, but culture went to shit quickly after that.
• Third I was also one of the first people and helped build a pretty exciting architecture from scratch. Stayed for 3,5 years, but unfortunately the company never found market fit during that time and the team never grew beyond ~20 people.

Overall I can say:

• If you value autonomy and you have a getting-things-done mentality this is the right gig for you.
• Culture differs very much per workplace, you may need to be lucky. (I don’t think that’s unique to startups though.)
• You need to be assertive and pro-active.
• Don’t do it for the money. Startups usually pay less, but in theory make up for it by offering equity. But most startups fail, so in most cases this will never be more than theory. Even if you do get an exit, chances are the payout is less than you would’ve earned working those years for a bigger corporation.
• The experience can be extremely rewarding because you can easily reach a position of influence.
• You will learn a lot.
• The experience can be frustrating because there is always pressure and a lot to do and you rarely have the means to do it all.
• You will need to improvise a lot.
• If you pull it off and your startup becomes successful the thrill is exhilarating.