Prototype or MVP: What Should You Build First?

A prototype is a sketch, linked screens, or coded simulation that makes an idea concrete enough to test. An MVP, or minimum viable product, is a first version people can use to complete a limited core task. It needs the privacy, security, accessibility, support, and reliability that task requires. “Minimum” means narrow scope, not unsafe or unfinished service. Teams use “MVP” differently, so agree what it means for your project.

Nielsen Norman Group describes a prototype as a hypothesis and notes that fidelity can vary in interactivity, visuals, and content. A realistic prototype can help test a detailed workflow; a lighter one is quicker to change. Match the fidelity to the question you need to answer. Read NN/g’s prototype guidance.

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This is a decision aid, not a universal sequence. You might prototype a risky interaction while engineering checks an integration. GOV.UK recommends prototypes that fit the question and testing risky assumptions before deciding what to take toward a live service. See its prototype and alpha guidance.

Write down the decision and the assumption that could change it. “Will people use this?” is broad. “Can a customer compare two options and understand the total cost?” gives you an experience to test.

For comprehension or navigation, a sketch may be enough; complex mobile interactions need a more realistic flow. If an external system must return data, add a technical check: a screen cannot prove an integration works. Questions about repeat use or transactions may need a constrained live release, if you can support it responsibly.

Hypothetical example: planning a group trip

Imagine an app that helps friends agree on dates and trip costs. Can each person enter availability and a private limit, then understand which option fits? A clickable prototype could simulate those steps. Ask a participant to add possible weekends, compare options, explain an estimate, and say whether the group has agreed. Observe where they hesitate. This may reveal usability problems; it cannot prove adoption or estimate accuracy.

Tandem is a UXPro studio concept that provides a visual reference: its people, trips, and costs are invented, and nobody has used or tested it. This example is hypothetical as well. It illustrates a question a prototype could explore, not evidence of demand or a Tandem result.

Give participants a believable goal without naming the controls: “You and your friends are trying to find a weekend that works. Show me what you would do next.” Watch what they expect. Avoid explaining screens, since that can hide problems.

Before sessions, agree on the research question, relevant participants, and prototype sections to test. Use accessible tasks and include people with different access needs where relevant. GOV.UK recommends realistic, neutral tasks and observation. Read the testing guide. Separate observations from interpretations. Usability sessions can uncover usability issues; they do not establish market size or forecast business performance.

Move toward an MVP when the core task is clear, prototype work has reduced key experience risks, and a live release can responsibly answer what remains. Keep the first scope small enough to support. Plan how it will handle real data, account access, errors, security, privacy, accessibility, support, and measurement.

Prototype code may not have production security or performance. GOV.UK warns teams not to copy prototype code straight into a live service. Carry forward the research and design decisions, then build and review production behaviour for the product’s needs.

Give the team the prototype, research question, task script, findings, open assumptions, and recommended next step. Add annotated flows and error or empty states for developers. Label simulated behaviour so screens are not mistaken for working features.

If evidence supports a release, translate the chosen flow into scope and acceptance criteria with engineering. If it does not, revise or stop before more build cost accumulates. UXPro can help through UX and UI design or mobile app design.