Andrew Crossley
    STAGE 1-2 · 2 WEEKS

    Product validation

    Product validation is the work of proving that a specific group of people has a problem they will pay to solve, before you build the solution. Real validation produces evidence of behaviour — money, signatures, repeated usage of a manual version — not opinions. Two weeks of validation routinely saves six months of building something nobody asked for.

    WHO THIS IS FOR

    You need validation if any of this sounds familiar

    • Everyone you have described the idea to says it sounds great, and nobody has offered to pay.
    • You are about to commit £20,000 or six months to a build based on your own conviction.
    • You have a waitlist of signups and no idea whether any of them would part with money.
    • Your target customer is 'small businesses', which is not a segment, it is a census category.
    • You have already built something and usage is flat, and you are not sure whether to iterate or stop.
    • An investor has asked what evidence you have and the honest answer is enthusiasm.

    THE FRAMEWORK

    The Crossley Method: idea to first revenue in seven stages

    See the full method
    1. STAGE 1DiscoverWeek 1
    2. STAGE 2ValidateWeek 2
    3. STAGE 3PrototypeWeek 3
    4. STAGE 4Build MVPWeeks 3-4
    5. STAGE 5LaunchWeek 5
    6. STAGE 6First RevenueWeek 6
    7. STAGE 7ScaleOngoing

    WHAT THE WORK COVERS

    Validation covers stages one and two

    Discover and Validate are the two cheapest stages in the framework and the two most often skipped. Everything downstream inherits their errors.

    Discover

    Find and talk to fifteen people in a tightly defined segment. Understand the job they are trying to do, what they do today, what it costs them and what they have already tried and abandoned.

    Validate

    Design a test where the only way to pass is for someone to change their behaviour: a pre-order, a paid pilot, a signed letter of intent, or sustained use of a deliberately manual version.

    Decision

    Kill, pivot or continue, against thresholds agreed before the test ran. Setting the bar afterwards is how founders talk themselves into building anyway.

    Handover to build

    If it passes, you go into Prototype with a defined segment, a validated problem, evidence of willingness to pay and a scoped first journey.

    HOW IT RUNS

    The two-week validation sprint

    1. Days 1-2

      Sharpen the hypothesis

      Turn the idea into a testable statement: this specific person, with this specific problem, will pay this specific amount. Vague hypotheses cannot fail, which is why founders like them.

    2. Days 3-6

      Customer discovery

      Twelve to fifteen structured conversations. Questions about past behaviour, never about future intentions — what people say they would do has almost no predictive value.

    3. Days 7-8

      Synthesis

      Patterns across the interviews, the language customers actually use, current workarounds and their real cost, and the segments where the pain is sharpest.

    4. Days 9-12

      Demand test

      A landing page with real pricing, a concierge version delivered manually, or direct pre-sale conversations. Something where a yes costs the customer something.

    5. Days 13-14

      Decision and next steps

      Written findings against the pre-agreed thresholds, and either a scoped MVP brief or a clear-eyed recommendation to stop.

    PRICING

    Validation pricing

    Deliberately cheap relative to a build. The entire point is to spend a small amount to avoid spending a large one.

    Validation review

    £1,200

    Two days. I review the evidence you already have, tell you what it actually proves, and design the test that would close the gap.

    Validation sprint

    £3,500

    Two weeks. Hypothesis, fifteen customer conversations, synthesis, a live demand test and a written kill-or-continue recommendation.

    Validate and build

    From £12,000

    The sprint rolled into a six-week MVP build if the evidence supports it. If it does not, you stop at the sprint and pay only for the sprint.

    Building rather than hiring? Get a number in 60 seconds with the MVP cost calculator.

    COMPARISON

    Real validation vs the thing most founders do

    The difference is whether the customer's answer costs them anything. Cheap yeses are worse than no data, because they feel like progress.

    FactorBehavioural evidenceOpinion evidence
    The question askedWhat did you do the last time this happened?Would you use something that did this?
    What a yes costsMoney, time or a signatureNothing, and it avoids an awkward conversation
    Signal strengthHigh — behaviour predicts behaviourNear zero, and systematically optimistic
    Typical outputThree pre-orders, or a clear no'Everyone I spoke to loved it'
    Cost to run£3,500 and two weeksFree, then £40,000 finding out
    What it changesWhether and what you buildHow confident you feel while building

    PROOF

    Validation in practice

    Wocal

    The first version served one venue manually before any platform existed. That concierge period is what revealed the actual job, and it is why the product reached 300+ venues and a £2.7M pre-money valuation rather than dying as a general hospitality tool.

    Co-Ride

    Founded November 2025 and currently in exactly this stage: community carpooling, tested with a defined local segment before committing to the full platform build.

    Ideas that got killed

    Several. The value of a validation sprint is measured in the builds that did not happen, which is an uncomfortable thing to sell and the most useful thing I do.

    Just Eat, 2021-2025

    Marketplace scale teaches you what genuine demand looks like in data, which recalibrates how much weight to give a friendly customer conversation.

    Why founders skip validation

    Not laziness. Validation is emotionally expensive. You have an idea you like, and the entire purpose of the exercise is to find out whether you are wrong. Building, by contrast, feels like progress from day one and does not require anyone to tell you no.

    There is also a speed argument that sounds reasonable: AI tools make building so cheap that testing by building is faster than testing by asking. Sometimes true. But building answers 'can this exist', while validation answers 'should this exist and will anyone pay'. A working product with no demand is a more expensive way to learn the same thing.

    The reconciliation is that validation and building overlap. A concierge version delivered manually, or a landing page with a real checkout, is both a test and the beginning of the product. What matters is that a real person makes a real commitment before you commit the budget.

    How to run a customer interview that produces signal

    • Ask about the last time the problem occurred, in detail. Specific memories are reliable; general opinions are not.
    • Ask what they did instead. Every real problem already has a workaround, and the workaround tells you the real competitor.
    • Ask what that workaround costs them in time, money or risk. If they cannot quantify it, the pain is not sharp enough to sell against.
    • Ask what they have already tried and stopped using, and why. This is where you learn what will kill your product later.
    • Never describe your solution until the end, and when you do, watch for whether they ask when they can have it or whether they say it sounds interesting.

    Demand tests that actually mean something

    Ranked by signal strength: a paid pre-order is the strongest, followed by a signed letter of intent with a named budget, then a paid pilot at a discount, then sustained use of a manual concierge version, then a deposit or waitlist with a card on file. A plain email waitlist is near the bottom — it costs nothing and predicts almost nothing.

    The landing page test is popular because it is fast, and it is useful with one condition: it must show real pricing and lead to a real attempt to pay. A page that collects emails measures curiosity. A page with a checkout measures intent.

    Set the threshold before you run the test. 'Three of fifteen conversations produce a paid pilot commitment' is a decision rule. 'See how it goes' is a way of guaranteeing you continue regardless of the outcome.

    What to do when validation says no

    Most of the time the answer is not a clean no. It is that the problem is real but the segment is wrong, or the problem is real and the pain is not expensive enough to command a price, or the segment and problem are both right and your proposed solution is not the one they want.

    Each of those has a different next move. Wrong segment means run the same test with a different group, which is cheap. Insufficient pain usually means moving up market where the same problem costs more. Wrong solution is the best outcome available short of a yes, because the customers have just told you what to build instead.

    And sometimes it genuinely is a no. Stopping at that point, two weeks and a few thousand pounds in, is the single highest-return decision available to an early-stage founder. It is also the one nobody celebrates.

    FREQUENTLY ASKED

    Product validation questions

    What is product validation?
    Product validation is the process of proving that a defined group of people has a problem they will pay to solve, before building the solution. It relies on behavioural evidence — pre-orders, paid pilots, signed intent, sustained use of a manual version — rather than on opinions collected in conversation.
    How long does product validation take?
    Two weeks is enough for a focused validation sprint: two days defining the hypothesis, four days of customer conversations, two days of synthesis, four days running a live demand test and two days deciding. Longer than three weeks usually means the hypothesis was too vague to test.
    How many customer interviews do I need?
    Twelve to fifteen within one tightly defined segment. Patterns become clear around ten and stop changing much after fifteen. Spreading the same number of conversations across three different segments produces confusion rather than confidence.
    What is the difference between validation and market research?
    Market research tells you how large a market is and what people say about it. Validation tells you whether specific individuals will change their behaviour for your specific solution. You can have a large market and zero validated demand for your product within it.
    Can I validate an idea without building anything?
    Yes. A landing page with real pricing and a working checkout, a concierge service delivered manually behind the scenes, or direct pre-sale conversations all produce genuine signal without a product existing. The test only needs to be real to the customer.
    How much does product validation cost?
    A two-day review of evidence you already have is around £1,200. A full two-week validation sprint including customer discovery, a live demand test and a written recommendation is around £3,500 — a fraction of the £12,000 to £25,000 a typical MVP build costs.
    What counts as enough evidence to start building?
    Three independent behavioural commitments from a single segment is a reasonable bar for an MVP: three paid pilots, three pre-orders, or three signed letters of intent with named budgets. Below that you are funding a hypothesis rather than a demand.
    I already built it and nobody uses it. Is validation still useful?
    Yes, and it is usually cheaper than another build cycle. The same discovery work applied to your existing users and churned users tells you whether the problem, the segment or the solution was wrong, which determines whether to iterate, reposition or stop.

    GET IN TOUCH

    Tell me what you are about to build

    The idea, the customer, and what evidence you have so far. I reply within 48 hours and I will tell you if you already have enough evidence to skip this.

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