Hi, my name is Leo Hannolainen
I work confidently with modern frontend frameworks and reliable backend technologies. My primary expertise lies in React and Next.js, where I build high-quality interfaces, component-driven architectures, and smooth user experiences.
I also have hands-on experience with Vue (Nuxt), Angular (including Angular Universal) and Rust’s Yew framework — giving me a broader perspective on frontend ecosystems and architectural patterns.
On the backend, I work with C#, ASP.NET Core, and Node.js (Express/NestJS), designing clean APIs, structured data models and maintainable application logic.
I enjoy solving complex problems, improving UX through thoughtful design, and delivering production-ready features with a strong focus on performance, scalability and code quality.
Developing a media platform featuring a global audio/video player, dynamic content sections, advanced search with highlighting, and a full admin dashboard. Designing and implementing both frontend and backend systems, including optimized APIs and structured data aggregation to ensure smooth UX, scalability, and reliable performance.
Contributed to the continuous development and optimization of the platform, implementing end-to-end tests with Cypress to improve reliability and adapting the frontend to evolving business requirements. Migrated static content and blog data to Sanity CMS, streamlining content management workflows, and updated SEO practices to align with modern standards and increase visibility.
Led the technical direction of the project, defining the architecture, establishing coding standards, and introducing a modular, scalable structure. Oversaw critical engineering decisions, enforced code quality through reviews, and ensured consistent integration of testing and documentation practices across the codebase.
Designed and developed a web application for managing digital display content across multiple university locations. The project streamlined a previously manual and time-consuming update workflow by delivering a centralized admin panel, a robust backend for data management, and a dedicated device-side client for real-time content delivery. The solution fully met stakeholder requirements and significantly improved the efficiency and reliability of the university’s content management processes.
Developed a modular prototype interface for a web application with a strong focus on clean architecture and maintainability. The project explored the benefits of a Feature-Sliced Design approach, implementing React components structured into feature-based modules. The interface supported task management functionality and included comprehensive unit and visual regression testing to ensure consistency and reliability.
Developed a desktop application enabling remote robot control, real-time monitoring, and
visualization of collected environmental data. Implemented live communication, data persistence,
and an intuitive interface for interacting with the robot during field tests.
This work was part of an international research initiative focused on environmental sensing and
autonomous robotics, supporting teams in conducting experiments and analyzing sensor output.
An application for managing smart devices.
This is a hobby project, we gathered friends to practice our skills in our free time, at the moment I
managed to make a
little part of the backend for web application and implement the MobX library, as well as learn how to
create
locales for
applications using i18n.
Developed the frontend for a tool that allows companies to generate and manage structured random data through an API and a dedicated web interface. Implemented a clean and intuitive UI for managing datasets and executing API requests, ensuring a smooth workflow for developers and QA teams using the service.
During my internship, I worked on improving a tablet application used across multiple university campuses in Lahti and Lappeenranta to manage classroom booking information. I rebuilt the application from the ground up, modernized its architecture, updated all dependencies, and migrated business logic from components to services to ensure long-term maintainability. I also enhanced the UI markup and introduced SSR support, gaining valuable experience in understanding when and where server-side rendering is beneficial.
Developed an MVP route-optimization tool for a delivery company, designed to help drivers and operators identify the most efficient paths between multiple locations. I implemented the user interface using React and integrated interactive map features with the Leaflet library. The solution allowed users to visualize routes, adjust parameters, and explore alternative paths, supporting faster decision-making and smoother logistics planning.
One of my Unity games, while doing this project I learned how to create on unity platform terrain levels, add different effects and make basic animations for objects. Thanks to this project , for myself, I realized that now, at the hobby level,creating games can be quite interesting and exciting.
The task was to build a weather station to monitor the atmosphere. The application sends data to the cloud, the gateway is “NodeMCU”. The operating system of the project was Azure IoT Hub. This work is the perfect solution for remote weather stations, home environment monitoring systems, and farm or garden monitoring systems.
Thanks to this project, I got acquainted with the world of IoT, and realized how promising this direction
is.
In this project, I was mainly responsible for the installing software and setting alert messages, but also
was actively involved in
connecting sensors and creating circuits for them
This project served as the starting point for the above project.
I'm always interested in hearing about new studying or working opportunities.