In a leaked memo, Shopify CEO Tobi Lütke put limits on employees having side hustles, saying Shopify requires ‘unshared attention’::Shopify CEO Tobi Lütke discourages employees from side hustles in company memo, saying their jobs require their undivided attention.
Depends on jurisdiction. Worth checking before taking any chances. Also worth considering that an employer willing to put that in the contract may well try to fire you and/or sue you if you come up with something valuable and they decide they want it, so even when you’re in the right it’s often not worth working for a company like that.