The CSP thin-slab technology (Compact Strip Production) provides a highly developed technical process for hot strip grades at low production costs. CSP combines the process stages of casting and rolling, which are discontinuous in the conventional process. This allows advantages to be achieved in terms of investments, energy consumption and operating costs. This paper describes the development work in progress, using the example of API steel grades. Key aspects of hot strip production such as alloying strategy, casting conditions, pass schedule design and the course of cooling are discussed and the resulting range of material properties is outlined. It can be demonstrated that CSP-produced hot strips feature very good toughness at low temperatures and may even allow applications which call for sour gas resistance.