A functional prototype is a working version of one part of your product, with a real backend, real data and often one real integration, built to prove that something works rather than to show how it looks. It differs from a clickable prototype, which is a designed simulation with no working logic. Functional prototypes cost $15,000 to $50,000 (€13,000 to €44,000, £11,000 to £37,000) and take four to eight weeks, and they are the right tool when the risk is whether the technology works, not whether users want it.
Prices are in US dollars. Euro and pound figures in parentheses are approximate, rounded conversions. Quotes are issued in the currency of your contract.
In plain terms
A clickable prototype is a film set: the facade looks real, and nothing behind it works. A functional prototype is one room of the real building, with real wiring and plumbing, so that you can test whether the design holds up. The rest of the building is not there yet.
Clickable versus functional
| Clickable prototype | Functional prototype | |
|---|---|---|
| What it is | Designed screens linked together in a design tool | Working software for one slice of the product |
| What works | Navigation between screens, nothing else | Real data, real logic, often one real integration |
| What it proves | The flow makes sense, users understand it, investors can see it | The hard part is feasible: the algorithm, the integration, the device, the performance |
| Cost | $5,000 to $25,000 (€4,500 to €22,000, £3,500 to £18,000) | $15,000 to $50,000 (€13,000 to €44,000, £11,000 to £37,000) |
| Time | Two to four weeks | Four to eight weeks |
| What happens to it | Becomes the design specification for the build | Often becomes the first slice of the real product |
When do you need a functional prototype?
- The core of the product is technically uncertain. A matching algorithm, a real-time feature, a hardware device, a machine learning model, an integration with a system nobody has documented.
- Investors or partners doubt feasibility more than demand. Seeing it work settles the question.
- A pilot customer needs to try something real. A business will not run its operations on a clickable prototype.
- The cost of being wrong about the technology is high. Better to spend $30,000 (€26,000, £22,000) proving it than $150,000 (€130,000, £110,000) discovering it does not work.
When is a clickable prototype enough?
When the technology is standard and the question is whether users want it and understand it. Most consumer apps, booking products, marketplaces and business tools fall here. The building blocks are known, so the risk is in the market, and a clickable prototype tests that at a fraction of the cost. Our guide to validation before code covers how to use one.
How does a functional prototype become the product?
If it is built properly, on the intended stack with the intended architecture, the functional prototype is the first slice of the real product, and the build continues from it. If it is built as a throwaway experiment, it is discarded once the question is answered. Both are legitimate. Decide which before it starts, because a throwaway is cheaper and a keeper needs more care.
Questions to ask your development team
- What exactly is this prototype meant to prove?
- Is it built to be kept or to be thrown away?
- What will we know at the end that we do not know now?
How 7L uses prototypes
Functional prototype development is one of our technical services, and it is the second phase of the Startupper Program. We build clickable prototypes when the risk is in the market and functional ones when it is in the technology, and we say plainly which one a founder needs. Tell us what you need to prove.
Frequently asked questions
Is a functional prototype the same as an MVP?
No. A functional prototype proves that something works, usually for a small group. An MVP is a complete, narrow product that real users rely on. A functional prototype often becomes the first part of an MVP.
Can I show a functional prototype to investors?
Yes, and for technically uncertain products it is more convincing than a clickable one. Pair it with evidence of demand, because it proves feasibility, not desire.
Should the prototype be built by the same team that builds the product?
Ideally, if the prototype is meant to be kept. If it is a throwaway, it matters less, but continuity of knowledge is valuable either way.