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Project background

Kontomierz app's main strength lies in its unique and intelligent transaction categorizer that outperforms comparable solutions available in most banking apps.

Kontomierz is a web application for personal finance management that dates back to 2009. The founder of Kontomierz - Kontomatik - sold the application in 2021 to Finelf.com, which became the new owner of this product.

Our client decided to improve and develop the existing product to help users make smart financial decisions by providing a tool that will transform their wallets and how they manage their finances.

Kontomierz users can create their own categories and subcategory groups and add transaction tags. Default categories don't limit them as it happens in banking apps - so they can carry out detailed analyses of expenses custom-tailored to their individual needs.

Such a solution helps to make educated decisions, which may result in the creation of specific limits for budgets (which is also one of the features) that will help them fit into the set savings goal. Kontomierz is an excellent tool for the challenges of today's expense management.

Kontomierz is a personal finance management app. Users have a complete picture of their finances. Kontomierz helps them track and categorise spendings. Optimizing personal budgets becomes easier.

Fintech industry

Kontomierz application is a digital product for personal finance management. PFM solutions aim to make the process of managing money easier and more efficient. To achieve this goal, PFM products utilize advanced algorithms and work with a vast array of data sources. 

This enables clients to automate the monitoring of their income and expenses and gain a comprehensive understanding of their financial situation. PFM solutions also facilitate the setting and achievement of both short and long-term financial objectives in a convenient manner. 

Overall, PFM solutions play a crucial role in improving financial education and cultivating positive financial habits among clients.

According to NMSC, the global personal finance software market was valued at 0.94 billion U.S. dollars in 2019. By 2030, the market is forecast to have a value of 1.69 billion U.S. dollars.

People nowadays use personal finance management solutions more often than before due to increasing awareness among individuals regarding the importance of financial planning and management in achieving their financial goals. 

Moreover, the availability of advanced and user-friendly personal finance management solutions, such as the Kontomierz application, makes it easier for individuals to manage their finances effectively. Such solutions can also be integrated with big data and artificial intelligence (AI), providing individuals with personalized experiences and real-time insights into their financial situation.



Categorization of expenses

Transactions are automatically assigned to one of the predefined categories. Moreover, the list of categories can be fully edited - the user can add parent categories, change their order, add and edit subcategories. Each category can also be marked with a user-selected color and icon.

Expense planner

It allows users to create budgets for individual categories or subcategories. Planning is limited to indicating the amount of the monthly spending limit and leaving a comment. The application suggests the total amount of expenses, also those not included in any of the budgets, and visually warns about approaching the limit.

Finance summary

Kontomierz offers a visual analysis of expense categories, a full breakdown of totals for categories, and a comparison of revenues with expenses. Options useful in ordering and analyzing transactions are also the possibility of dividing them into several operations (e.g., dividing purchases based on a receipt into groceries and others) or tagging them.

DEMO mode

The DEMO mode of Kontomierz differs from standard solutions. This application offers free access to the DEMO mode, which is maintained for a week for each unregistered user. At this time, a user has access to all of the app’s features which can be tested on sample data. The DEMO version is always updated to the newest version of the product.

Scope of work

The system and some of the earlier solutions of the Kontomierz app needed to be updated; the previous version of the app became a blocker for our client to develop their product further.

Kontomierz app as a Fintech product needed to adapt its design and features to the current needs and trends of the market.

LeanCode team consisting of 2 Backend Developers, 2 Frontend Developers, a Product Owner, and a UX Designer was responsible for the entire product development, which was divided into five phases:

  1. Designing a new look&feel and improving the User Experience of the application.
  2. Recreating some of the features from the previous app version.
  3. Migrating data from the old version of the app.
  4. Implementing subscription payment options.
  5. Developing new features.

Our client's product needed to refresh its branding and how the application looked inside. In Kontomierz, the user has access to a large amount of data which might be overwhelming. Our team conducted workshops with a client dedicated to defining the main target groups and mapping user stories, significantly impacting the new design.

The design implementation process went quickly thanks to the access to Design System by LeanCode. Standard elements of the app, such as buttons or text fields, didn’t have to be designed from scratch and could be easily adapted to the selected brand, which speeded up the entire process, especially with multiple screens available in the app.

The experience of our design and frontend team was also an asset while developing numerous charts summarizing the user's finances and expenses that the user can access while analyzing personal finances via Kontomierz.

To improve the resilience and maintainability of carrying out multi-step and complex processes, our backend team designed a few so-called “state machine sagas”, which have prepared Kontomierz backend for processing long-lived, resource intensive and distributed transactions, where the data had been collated from one or more sources and inserted to one or more destinations.

Examples of such processes are: bank account data import and old Kontomierz account migration. They are heavy ETL (Extract - Transform - Load) processes, so they deserved their own microservice, which allowed us to scale them efficiently according to their needs.

Each step had to be limited to processing a specific number of transactions at the moment not to overwhelm the system. Another process that required using the saga pattern was Kontomierz account removal, in which data had to be cleared in many distributed services.

Another challenging process that our backend team handled smoothly was integrating Kontomierz with the user’s bank account so they can view and categorize all the transactions. We used Kontomatik’s open banking integration, which provided a secure bridge for the flow of financial data between banks and customers using an open banking API. We injected bank account data into the Kontomierz system, processed transactions (including exchange rates) and filtered out duplicates.

Other solutions used in this project were integrations with:

  • BillTech - a tool for recurring bills and subscription payment management.
  • Ory Kratos - headless and configurable authentication and user management system, including MFA, social login, custom identities.
  • Stripe - payment processing platform used for online subscriptions.

Technologies also used were: React, TypeScript, .NET, Azure, Terraform, SQL Server and PostgreSQL.

Our client took advantage of our technical experience and relied on our recommendations during the entire product development process (IT consulting service). The client trusted our expertise, but also actively participated in every stage. As a result all users can benefit from a great PFM product - Kontomierz.

Review of our work

Kontomierz logo

Working with LeanCode is at a very high level! LeanCode has skillfully delivered the project as per the client's requirements. The service provider ensures effective and productive communication through meetings, interviews, and email. Their commitment, project management, availability, and supportive approach are key elements of their work.

Marzena Wójcik
Marzena WójcikProduct OwnerFinelf.com
Meet our expert

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Łukasz Kosman, CEO LeanCode
Łukasz KosmanCEO at LeanCode

Key takeaways

  • Financial applications require handling complex integrations, security, transactional solutions, and risk management. In some cases, skills have to be combined with earlier experience and gathered knowledge to be implemented properly and efficiently.
  • When cooperating with a software house such as LeanCode you can benefit from their internal packages and solutions such as integrating apps with the Stripe payment processing platform used for subscriptions. It shortens the time of development.

Additional value delivered

LeanCode often offers its clients unique internal solutions that speed up product development without sacrificing code quality. We also met all client’s deadlines and adjusted the order of feature implementations to their business needs.

LeanCode Design System

LeanCode experience in Fintech products

Fast product development


Azure icon
Microsoft Azure
Terraform logo

Awards & press releases

Bankier.pl logo
“Functions supporting the organization of home finances can already be found in almost every bank. Their most common disadvantage, however, is the lack of the possibility of more precise personalization. For those who want to have more control over their notes, the new incarnation of one of the oldest Polish PFMs - Kontomierz may be attractive.”

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Meet our expert

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Łukasz Kosman, CEO LeanCode

This is the initial scoping call. Its purpose is to get a better understanding of what you want to build. After this call, you will have an idea about your project's feasibility and the ballpark estimates.

Łukasz KosmanCEO at LeanCode