Idea Validation: Product

Working Prototype

Build just enough of a feature to test its intended behavior

Illustration of Working Prototype
Run a Working Prototype play

Also called: Digital Prototype, Clickthrough Prototype

Difficulty: Hard

Evidence strength

Relevant metrics: Acquisition, Activation, Cycle time, Customer feedback, Cost

Validates: Feasibility, Viability, Desirability

How: With the least effort possible and without much regard to scalability or internal quality, build just enough of a feature to be able to test it with your target audience. Identify the epicenter and core of your product and implement just enough for users to understand its value and purpose.

Why: Disregarding scalability, code quality, and even design quality will allow you to build a simple, but working version of the feature you want to test, faster than building the real product.

This experiment is part of the Validation Patterns printed card deck

A collection of 60 product experiments that will validate your idea in a matter of days, not months. They are regularly used by product builders at companies like Google, Facebook, Dropbox, and Amazon.

Get your deck!

Before the experiment

The first thing to do when planning any kind of test or experiment, is to figure out what you want to test. To make critical assumptions explicit, fill out an experiment sheet as you prepare your test. We created a sample sheet for you to get started. Download the Experiment Sheet.

The importance of working prototypes

A working prototype is a precursor, a harbinger of a product that is constructed to test a concept or process. It serves to demonstrate to investors and marketing companies the viability of an idea.

It is essential not to underestimate the significance of a working prototype. Attempting to cut corners by skipping the functional prototype stage and moving forward without having demonstrated the functionality of your product to yourself and others would be a grave mistake. The adage holds true, “a picture is worth a thousand words,” and a working prototype will effectively convey the seriousness and professionalism of your new product or invention.

The process of building a working prototype

To achieve the desired level of fidelity, working prototypes are implemented with the bare minimum necessary to collect feedback from users as if it were a finished product. For physical products, 3D printing, fabrication, and the utilization of “off the shelf” parts are commonly employed to construct and develop functioning prototypes. Conversely, for digital products, real coding is employed to make light features work as if they were in the final product.

The process of building a working prototype involves creating a functioning digital or physical model of a product’s design that a target user can then test. Understanding how to create a prototype is a crucial step in the journey of transforming an idea into a manufactured product.

Why create working prototypes?

Building a working prototype can yield many benefits:

  • Assessing Functionality. Building a model of your proposed idea can aid in determining whether your product functions as intended. After testing your product with a prototype, you can determine whether it is worthy of further investment in time and money. Furthermore, it allows for adjustments to be made to ensure optimal performance and customer satisfaction.
  • Cost-Effectiveness. Creating one or two prototypes is typically a less expensive process than mass-producing a product without testing it first. This is because a prototype allows for the perfecting of the product’s design before incurring the expense of production and potentially having to recall the product due to defects. Additionally, it can be used to ensure the production process is economically viable.
  • Demonstrating to Investors. A prototype of your product can also aid in showcasing to investors what your product aims to accomplish and how well it works. It also offers the opportunity to answer any questions they might have about the product, thereby convincing them of its worthiness as an investment.
  • Determining Usefulness. Allowing select members of your intended audience to use your prototype can help determine whether they find the product to be useful. Feedback can be gathered to learn more about what they like and what might require improvement, leading to the creation of an even more useful prototype or advancing towards mass-production.
  • Highlighting Appropriate Materials. A prototype can aid in determining specific materials required and the outline of the eventual product’s shape. It can also help determine that changing the shape or fastening parts together differently can make the product sturdier than originally believed.
  • Facilitating Discussions. Developing a prototype can provide specific, clear answers to questions about the product’s dimensions, weight, mobility, and other aspects. This can aid external parties in determining whether they want to invest in or assist with the final product.

When is my working prototype ready for production?

The mockup process, from the first working prototype to the last, is a costly and time-consuming endeavor that can be mentally taxing. Through extensive testing, reworking usability issues, and rethinking design decisions, you might ultimately arrive at a product that is ready to take to market. A conclusion might also be that your product idea is not better than current market standards or just doesn’t have a market to serve.

Problem-solution fit vs product-market fit

A working prototype focuses more on problem-solution fit than product-market fit. A working prototype is an early example, model of a product built to test a concept or process to be learned from or to show investors and marketing companies. It allows for testing of the product’s functionality and usability, and it can help to identify and solve any issues that may arise with the design. However, a working prototype is not necessarily a good way to test whether a product has merit in a market.

Product-market fit is the process of determining whether there is a market for a product and whether the product is the right fit for that market. It involves researching target customers, understanding their needs and pain points, and determining whether the product can effectively solve their problems. While a working prototype can help to test and improve the problem-solution fit, it may not necessarily be able to test whether there is a market for the product.

For example, a working prototype of a product may function perfectly and solve a specific problem, but it may not be something that people are willing to pay for or that they even need. In contrast, a product-market fit evaluation would test whether there is a demand for the product and whether it is a good fit for the target market. Therefore, a working prototype is a useful tool for testing and improving the problem-solution fit, but it is not the only tool that should be used to evaluate a product’s potential in the market.

Testing problem-solution fit

However, a working prototype can help determine whether a solution works well to solve a specific problem. In this regards, consider the following four qualities:

  • Problem Solving. It solves the problem you set out to solve.
  • Expected Results. It gives you the results you’re looking for.
  • Differentiation. It differentiates itself from other similar products on the market.
  • Superiority. It’s the best option out there.

Ultimately, a successful product-solution fit comes down to the user experience. If the user experience cannot be improved upon by other products, the prototype may be ready to be market-tested.

What should you test?

Intention and customer problems

To ensure your project is moving in the right direction, consider the following questions as you create your prototype

  • User Expectations. Before users even view the prototype, what would they expect to be able to do with it? How would they expect it to look?
  • Comprehension. Once the prototype is shown to users, do they understand what it does? How does it measure up to their expectations?
  • Missing Features. What features are missing from the prototype?
  • Design Elements. Does anything seem out of place or unnecessary?
  • User Experience. How do users feel when using the prototype?
  • Wishlist. If users had a magic wand, what would they change about the product?
  • Likelihood of Use. How likely are users to use this product once it is finished?

First glance

A critical aspect of the design process is ensuring that the design effectively communicates the purpose and functionality of the product or website at first glance. To validate this, consider the following questions:

  • Product Purpose. What do you think this product is for?
  • Functionality. What do you think can be done on this website, in this app, or with this product?
  • Use Case. When would you use this product or website?
  • Target Audience. Who do you think this tool is for?
  • Associations. Is there anything this tool resembles? If yes, what?
  • Confusion. What, if anything, doesn’t make sense in the design?

Tasks specific use-cases

To effectively evaluate the usability of your website or product, it is essential to develop task-specific questions that align with the actions users will take within your industry. There are no catch-all questions in this category, as that will depend solely on the specific product you are developipng. However, consider the following examples for inspiration.

E-commerce and Retail

  • How did you recognize that the product was on sale?
  • What information about shipping was missing, if any?
  • What were the accepted payment methods?


  • How did you know the plan you picked was the right one for you?


  • Do you think booking a flight on this website was easier or more difficult than on other websites you have used in the past?

Banking and FinTech

  • Did sending money via this app feel safe?


  • Do you think data gathered by this app is reliable?


As you evaluate your prototype, it is crucial to address any lingering concept, flow, or basic usability issues. To do so, consider the following questions:

  • Functionality. Does the prototype fulfill its intended purpose?
  • Design Alignment. Do users believe the product’s design aligns with its intended purpose?
  • Intuitiveness. What is the first action users would want to take on the product? Can they do so easily?
  • Confusion. Does exploration of the product lead to confusion at any point?
  • Distraction. Are there any elements that distract or impede the user experience?
  • Ignored Features. Are there any features that are consistently ignored by users?
  • Information Architecture. Does the information architecture and navigation make sense? Can users easily find what they are looking for?
  • Target Market Relevance. Does your target market feel that the product was designed for them?
  • Frequency of Use. What would make users want to use the product frequently?
  • Recommendation. How likely are users to recommend the finished product to a friend?
  • User Description. How would users describe the product using their own words?

Planning your next session: Recruiting future testers

Instead of recruiting brand new participants for each testing session, consider asking current testers if they would be interested in participating in future research. Additionally, inquire if they know of anyone else who might also be interested. Ask:

  • Would you be interested in participating in future research?
  • Who else should I talk to?

Who else should I talk to?

When budget allows, consider utilizing software tools that allow for remote prototype testing. Then, recruit a few select users who would be interested in coming in for a more in-depth session. This approach allows for the selection of participants based on the quality of feedback provided during initial testing, rather than bringing in participants who may not offer the same level of insight.

If you are interested in learning more about how to test your prototype, be sure to check out a step-by-step guide for helpful tips. You will find this original list of questions, as well as in-depth information about the benefits of prototype testing, deciding what to test, task scenarios, and more.

Cheaper ways to test?

While it’s better to test on a Working Prototype rather than a final product, the high fidelity of the prototype, i.e. the high level of detail and interaction, also comes with an economic price tag. Working Prototypes can be a very expensive way to test your hypothesis. Consider going for Paper Prototypes or Clickable Prototypes before spending time creating a working prototype.

Yet, some things can’t be tested with lower fidelity prototypes or product experiments, why creating a Working Prototype might just be what you need to move forward. Especially when it comes to prototyping physical products. In this regards, you might want to consider building a cheap LEGO prototype mock-up of what you want to end up with, first.

After the experiment

To make sure you move forward, it is a good idea to systematically record your the insights you learned and what actions or decisions follow. We created a sample Learning Sheet, that will help you capture insights in the process of turning your product ideas successful. Download the Learning Sheet.



Chesky and Gebbia rented out air mattresses in their apartment to test the concept of peer-to-peer room and home sharing. This initial experiment helped validate the demand for a platform like Airbnb, leading to its development and success.

Source: How 3 guys turned renting an air mattress in their apartment into a $25 billion company

This experiment is part of the Validation Patterns printed card deck

A collection of 60 product experiments that will validate your idea in a matter of days, not months. They are regularly used by product builders at companies like Google, Facebook, Dropbox, and Amazon.

Get your deck!

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