Chroma Experience

SteelBuy — digital marketplace for trading metals

As a start-up incubator, we developed SteelBuy, a digital solution for trading metals as an innovative B2B platform. By working closely with industry experts using an iterative approach, we have made trading metals more efficient, transparent and time-saving.

This solution has the potential to be a game-changer for the entire steel industry and a benchmark for higher standards.

Steel Coils


SteelBuy Ltd.
Investor: thyssenkrupp Material Services

Fields of activity

Industrial goods, B2B E-Commerce


Digital transformation and Anonymisation of conventional trade in metals


Development of a B2B marketplace for seamless and efficient trade in metals


Consulting, conception, software architecture, product strategy, experience design, visual design, front-end engineering


React, NX, Redux, Thunk, Sass, Jest

Summary of the project


Contractual arrangements in terms and conditions about purchase quantities builds the foundation of the traditional trade in the steal industrie. Therefore, the main instruments for buying and selling metals are telephone, e-mail and fax.

The need for sellers to keep their competitors in the dark about excess inventory, as well as the effort required to find buyers, intensify the inertia in the steel market caused by traditional trading methods. Consequently, the difficulty for buyers to find these stocks and for sellers to identify the appropriate buyers increases.

In addition, the sale of surplus stock is time-consuming and connected with low margins.

To meet these challenges, it was necessary to develop a business model and product solution that would digitise and at the same time greatly simplify the trading of industrial metals.

Approach, activities and solution

The vision for the product served as the foundation for the development of the SteelBuy platform, created in collaboration with our partners BCG X (formerly BCG Digital Ventures). During the pre-operational phase, market analysis, initial business model creation, and product sketch development were undertaken to design the product.

Our product, which was designed on the base of the requirements and our business model, conceptualised by domain experts, encompasses all aspects of trading, including the sales, purchase, delivery and quality assurance.

The iterative product development process was tested through user testing, beginning with the initial concept and culminating in a minimum viable product (MVP). Meanwhile, the product development and the establishment of the start-up as an organisation progressed in parallel with the evaluation of the business model, which was tested to identify solutions for operational implementation.

Multiple work streams were simultaneously engaged in the implementation of the business idea. Consequently, it was essential to regularly synchronise the results to promptly respond to any changes.

To offer shareholders a transparent overview of progress and enable them to provide input and significantly influence future development, the interim results have been consolidated with thyssenKrupp Material Services, the principal investor.


We have successfully developed a product that streamlines slow processes through an efficient, user-friendly interface. Eight months after the initial kickoff, the launch of the SteelBuy platform represents a transformative approach to material trading, with the potential to revolutionise the entire industry.

Time to market

8 months

Venture Team

31 People

Reduction of the administrative effort

40 %

SteelBuy Produkt-Mockup
SteelBuy Mockup – Produktsuche
Carousel Wide 1.jpg

tkMX Corporate Ventures

The concept of digitising the steel industry is well established. Numerous earlier initiatives have demonstrated the slow pace of trade, with some even failing in their attempts to enhance the process. One such example is Mapudo:

Terry Sargeant (CEO of SteelBuy Ltd. and former CEO of thyssenkrupp Materials UK) succeeded in generating interest in a B2B marketplace solution. Through the internal Shark-Tank-format of tkMX (thyssenkrupp Material Services), he secured development funding for a proof-of-concept.

A website for managing excess inventory was developed within the constraints of limited resources.

The offer underwent regular updates and was exclusively accessible to a curated group of interested parties. A substantial volume of products were swiftly sold, demonstrating the potential to streamline the traditionally sluggish process from inquiry to quotation to transaction, thereby enhancing efficiency.

The business concept was shown to be viable in principle. However, the next step was to determine the economic potential of the market, to define the product design required for sustainable market establishment and to strategise the scalability of the business model.

BCG X was entrusted with this task. In a feasibility study lasting several weeks, the vision for SteelBuy was developed and presented to the tkMX board.

Terry Sargeant
Terry Sargeant CEO, SteelBuy

When building a product and a platform/marketplace, choosing the right partner is crucial. Partnering with Chroma X accelerated our development process and ensured a structured, design-led approach. The team at Chroma became fully embodied in our development team, playing a key role in building an exceptional marketplace. Steelbuy (a subsidiary of thyssenkrupp) remains delighted with our decision to partner with Chroma X.

BCG X Chroma

Following the Series-A financing, the task at hand was to secure an experienced service provider for product development. Following constructive discussions with Terry Sargeant and Ilse Henne (Board Member of thyssenkrupp AG and former Chief Transformation Officer of thyssenkrupp Material Services), we successfully positioned ourselves as the service provider and commenced collaboration with BCG X, who had already been designated as development partners.

The project was divided into three working groups: Business & Go-to- Market, Product, and Venture. Our area of responsibility, Product, encompassed all aspects from strategy to discovery to delivery. An agreed-upon approach model at the outset ensured a highly open, transparent, and constructive collaboration. Affiliations with various companies were quickly set aside, and together we became the SteelBuy team.

In parallel with the product realisation, the venture was not only established as a legal entity, but also staffed to support the recruitment of people and roles to continue the work post-incubation.

Dr. Sebastian Smerat
Dr. Sebastian Smerat CEO, Smart Services – thyssenkrupp Material Services

The collaboration with Chroma X was productive and transparent from the very beginning. Their ability to translate complex requirements into a functional product has made an important contribution to the success of SteelBuy.

Re-framing and identifying user requirements

At the beginning of the project we worked with an initial static prototype, which was used to visualise the vision of the project. The result was based on various interviews with different market participants. For the actual product realisation, it was essential to evaluate the collected results and compare them with the requirements of the primary user group and bulk purchasers of raw materials.

SteelBuy – Process Diagram
SteelBuy – Match Making Wireframes
Navigation Architecture

Business model transformation

Traditional steel trading is anything but digital. It's usually based on a contract between seller and buyer. Customers with a short-term demand for steel products, often reach out to multiple sellers to obtain various offers. The entire process, from the initial inquiry to completed transaction, can span several days. In addition to a broad network, excellent communication skills are crucial for achieving success in this context.

If a retailer offers products at unusual low prices, competitors become aware of their excess stock. Consequently, sellers face the challenge of offloading surplus inventory only with difficulty and under unfavorable conditions. Additionally, there is a risk that existing customers will demand to purchase products under the same terms.

Overall, the effort involved in managing overstock is disproportionately high compared to the returns.

SteelBuy addresses these and many other challenges with its product promise, offering an innovative solution to streamline and improve the efficiency of handling excess stock.

Diego lago
Diego lago Head of Product and Innovation, SteelBuy

Partnering with Chroma X was pivotal for the launch of our B2B online marketplace. Their team closely collaborated with our domain experts, quickly gaining a deep understanding of the metals industry and identifying possibilities for innovation. This insight significantly enhanced our initial strategy and design. We are immensely grateful for the solid foundation they helped us establish and their lasting impact on our project.


The value of user interviews

Learn more

Product from definition to delivery

The product definition was the first milestone, encompassing the scope of the solution in three distinct phases with various intermediate stages: the Earliest Testable Product, Earliest Usable Product, and Earliest Releasable Product. These phases are part of the BCG X approach, designed to evaluate the business model at an early stage.

The product definition phase was constrained to a maximum duration of four weeks, within a total incubation period of seven months. By employing methods such as use cases, service blueprints, and business process diagrams, we identified the key functional features essential for fulfilling the business objectives.

By the end of the first phase, the product was ready for testing: the software architecture had been defined, the general operating concept and visual design had been evaluated, and the initial functional components were in place. While the design team integrated the business requirements into the product and tested its acceptance with potential users using prototypes, we consolidated the results in engineering and rapidly developed a complete product.

Sales Director Service Center

I was unsure at first. It felt wrong but as soon as I got into the system, and realised how easy it is to use, I knew this was what we needed. So fast, SteelBuy will certainly be a new sales channel for us.

Matchmaking at Scale

One of the most critical factors for lasting success was the process of matchmaking. The primary question to address was how customers find products online and how sellers effectively advertise their products. We connected with domain experts to catalog the taxonomy of various steel products and record their respective properties within a defined set of rules.

Using evaluation criteria that are used for the ideal selection of suitable steel products, we developed an algorithm that not only finds the right product based on a search query, but also makes intelligent suggestions for similar alternative products.

The algorithm utilises the expert knowledge of steel industry professionals with over 20 years of professional experience to deliver results that are of great value to buyers and sellers alike.

SteelBuy – Mobile Application
User Interface – Deal Radar and Smart Matchmaking results
SteelBuy smart product search step 1
User Interface – Guided Product Search
SteelBuy smart product search step 2
User Interface – Product Listing


From vision to delivery in just seven months, we managed to develop SteelBuy, a product that is revolutionising conventional steel trading. An innovative platform was created that makes trading metals more efficient and transparent in close co-operation between the partners SteelBuy, thyssenkrupp Material Services, BCG X and Chroma X.

The team was able to make ongoing optimisations and achieve a high level of acceptance among industry experts because of the iterative approach and continuous feedback.

SteelBuy continues to attract new users and expands its range of materials. It is supported by a product that is focused on business objectives, tailored to the specific needs of users and has changed little since its release in November 2022.

Design-Komponenten – Ressourcen
Design-Komponenten – Custom Illustrationen
Design-Komponenten – Komponenten
Design-Komponenten – Kompositionen
Product Management
Paul Lewandowski
Requirements Engineering, UX-Research
Florian Köppe, Kalina Kondeva
Visual Design Lead
Ilona Maslioukovskagia
Technologie-Lead, Software-Architecture
Martin Brecht-Precht
Experience Design
Florian Köppe
Visual Design
Maximilian Milkereit
Frontend Engineering
Stefanie Große-Bölting, Felix Gyamfi

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