A Concierge prototype is very similar to a Wizard of Oz prototype in the sense that you will try to fake most of the necessary backend capabilities of your envisioned product while you test it with potential users. Where this prototyping strategy differs is that you are open about the fact that you are currently replacing tech capabilities with one or more human substitutes. Example: You want to offer a new Robo financial advisor that continually tailors its advice and investment strategy towards a user’s current mood. Instead of investing the time to build the digital interface to interact with the user and the necessary backend capabilities of the service, I could advise a few selected “early” customers via daily phone calls and e-mails. During the phone call, I can find out what their current mood is and suggest adjustments to their investment strategy. If their portfolio is adjusted, I can let them know in a well-crafted e-mail, which shows the current composition and performance of their portfolio. Now, this is a silly example – or at least it goes against all the financial advice I have been given so far – but it illustrates how this prototyping method could be used. In general, a concierge prototype will help you to test general assumptions about your envisioned product, while also digging deeper into understanding the needs, pains, and behaviour of your target group. As a bonus, a well-executed concierge prototype often helps with getting your foot in the door of potential customers for your future product. If they liked your personal financial advice, they should also be more inclined to try your digital Robo financial advisor, if you chose to build it.