key4 enables prospective home owners to find a very attractive financing for their dream home. The solution is simple, transparent, independent, free of charge, and is built around the individual financing needs of its users.


How does key4 work for partners?

Partners typically have relevant touchpoints with potential mortgage leads through their own business operations. By integrating the key4 mortgage offering process into their environment, our partners can provide a seamless and convenient experience to their clients.

Partners simply integrate the Mortgage Offer API into their website. This allows the partners’ clients to calculate a real-time indicative mortgage offer on the partners’ website.

How does key4 work for prospective home owners?

With key4, prospective or existing home owners can obtain a non-binding mortgage offer with real interest rates within minutes.

Home owners just enter a few essential inputs and will immediately receive non-binding offers from various Swiss loan providers. It is possible to combine offers from various providers to create a personal total financing solution.


How can I become a partner with key4 to use the APIs?

Let us evaluate a partnership with you. Please write an email to

Which API's are available in the key4 ecosystem?

Our partners can use the Mortgage Offer API to calculate an individual mortgage offer for a given real estate object and financial situation. The output of the Mortgage Offer API is:

  • Interest cost per month

  • Interest rate