proofkit

Stop guessing
your price.

ProofKit runs Van Westendorp's Price Sensitivity Meter and the Sean Ellis PMF survey, then translates the math into plain-English findings.

Create your first survey

Free: 2 surveys, 50 responses each.

Van Westendorp - example data, n=34 100% 0% $5$15$25$35$45 OPP $26

drag the cursor - the finding updates live

Two surveys every team cites. Almost none run.

Van Westendorp

pricing

Four questions per respondent produce the acceptable range and the optimal price point.

  1. too cheap to trust?
  2. a bargain?
  3. getting expensive?
  4. too expensive?

Sean Ellis PMF

benchmark 40%

One question: how would you feel if you could no longer use the product? Very-disappointed share above forty percent signals product-market fit.

40% the bar

The interpretation is the product.

Spreadsheets give you curves. ProofKit writes the findings section of your deliverable:

Your optimal price point is $26, sitting inside the acceptable range of $19-$41. The point of resistance is $33; price above it only for premium segments.
auto-generated sample finding - VW survey, n=34

Methodology older than your startup.

Van Westendorp's Price Sensitivity Meter, 1976.

Fifty years of use in consumer research, reduced to four questions and four curves.

Sean Ellis's 40% test, 2009.

The PMF benchmark used by Superhuman, Segment, and half the case studies in your bookmarks.

Against the spreadsheet incumbent.

ProofKitTypeformDIY Sheets
VW math built in yesnoby hand
PMF 40% benchmark yesnoby hand
Plain-English findings yesnonever
Respondent accounts noneannoyingn/a
Cost to start $0$$your evening

positioning summary, 2026

“I ship a Van Westendorp study in every pricing engagement now. Clients think I have a research team.”

Claire Dubois

Product consultant

sample feedback

free tier

Run the survey you keep citing.

Two surveys and a hundred responses before any payment.

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