case study

Rapid prototyping using the lean UX-Method

case study


This case study is a great example how I love to work:
In a small cross-functional team we validated a concept business idea through rapid prototyping using the lean-UX method. Quick results, top skills where combined and a lot of friends made.

2 app prototypes (1 for private consumers and 1 for brick-and-mortar stores) where designed, developed and tested (no click-dummy) within 3 months.

worked for (client)

Market-leading couponing and voucher portal.
~ 80-100 employees




Business analyst, Product owner, UX designer, full-stack developer

For the sake of discretion, no details about the application and customers can be given.

tools & methods

The core competencies and methods we used during the project.

Business strategy & marketing

Business model canvas
Value proposition
Stakeholder workshop

technology research

NFT, QR-Code and other scan methods where tested.

Agile Project management

Lean UX

UX Research & Design

User interviews
Competitor analysis
User testing
Flow charts
UI design (Material Design library)


my role

as we where a small team, I was involved in all aspects of the project, except for the full-stack development.

The situation

The commissioning e-commerce company - a wide-reaching Internet portal for online retailers and private end users - where looking to expanded to other target groups. 

The associated investment risk was assessed as high, which led to uncertainty in the decision.


The company believes that the existing offer on the online platform will be valuable for - offline - brick-and-mortar retail and offline services.

The desire

The assumption should be validate first (problem-solution-fit) before the marketability would be tested in a further phase (product-market-fit).

The problem

Internally there was limited capacity and little experience in prototype-driven development.

understand & observe

start & preperation


business model canvas

An interdisciplinary project team was set up at the client’s office. We independently carried out the entire product development process in close cooperation with the client's management team and the internal staff.

The starting point was a joint business model (canvas).

understand & observe

user interviews


Value Proposition Canvas

We organized workshops with internal staff, who already built up a lot of knowledge about their audience. In the workshops we collected hypothetical customer values and needs (value proposition canvas).

In user interviews with the target audience these problems and needs where validate.



2 user groups

Based on the data and business requirements we focussed on two user groups


Web-based apP

owners of local shops & services

- set up their user account  
- create voucher campaigns independently


native iOS and Android app (Ionic framework)

(local) consumers

- find available promotions and coupons in real time
- display promotions which they could activate and show to the service provider to get their promotion.

understand & observe

Competitor analyses

Besides conducting the user interviews we also did a competitor analysis where we derived weaknesses, potentials and user expectations from the offers already available on the market.

Ideate & prototype


prototype & test

user testing

"There are no facts inside the building. go outside!"


No click-dummy

Within 3 weeks we designed and developed two apps, using material design library and the ionic framework.

We then made the apps available to the local shops and to the client's employees for a beta test.

The apps where tested in real operation over a period of several weeks. (no click-dummy, no pre-organized user tests)


Feedback & iterations

During testing the consumer had easy access to a feedback functionality.

Feedback from consumers and shop owners where recorded and evaluated using the app itself and, if necessary, implemented immediately as part of a lean development based on user needs (Lean UX).

story & presenting

presenting the outcome

"communicate & share learnings"

Final assesment

Finally, qualitative interviews and the analysis of usage volume and behaviour followed.

The hypotheses collected at the beginning of the project were verified or falsified and based on this, an assessment of the potential solution was made and presented to the client.


skill share

Coaching the internal staff

During the whole project we invited the internal staff to come visit us on ‘Donut Dienstag’ (Donut Tuesday). In these meetings we presented our progress, brainstormed ideas and showed the methods and tools we used.

Additionally I created an Instagram account where employees could follow the project.

“By being integrated in the team it is easier to identify the company culture and advise the client what the biggest issues are, and how to optimise their (working) habits.”
the result



Business idea tested within 3 months

The customer was able to go through a complete digital product development almost ‘from scratch’ within 3 months and gain crucial insights into a business idea.


Running OPERATIONS WERE not affected

As the team was set-up out of external consultants this was possible without having to deduct one's own capacity from the further development of the main product and suffer high opportunity costs.


New method presented and coached

At the same time the user-centric method was implemented hands-on and internal employees where inspired and motivated to continue using this -new- method.

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