InvestEngine is a UK investment platform exclusively dedicated to helping you build a portfolio of ETFs (on your own or through a "Managed Portfolio" service with an annual fee of 0.25%). It also offers an ISA and Business account.InvestEngine is a UK investment platform exclusively dedicated to helping you build a portfolio of ETFs (on your own or through a "Managed Portfolio" service with an annual fee of 0.25%). It also offers an ISA and Business account.