Tuukka Haapasalo

IQM Resonance

Customers and researchers use IQM Resonance to run computations on quantum computers built by IQM, a Finnish quantum-computing company. It started as a public cloud service and now also sits in front of the quantum computers IQM sells to its customers. As of 2026, the public cloud offers three machines, the largest with 54 qubits.

I’ve been on the project since the start of implementation. A colleague and I designed most of the architecture. I’ve worked on the service’s user interfaces and on the backend server that queues quantum jobs and dispatches them to the machines. When the Python implementation’s performance and maintainability were no longer good enough, we rewrote the server in Rust. The team has varied in size from about five to fifteen people.

• Rust
• axum
• PostgreSQL
• React
• TypeScript
• Python

Telia Dot

Telia Dot is a fully digital mobile operator that we built for Telia. It runs on Telia’s mobile network and backend systems, and customers manage their subscription entirely through a mobile app.

I joined at the start of implementation. There were about fifteen of us, and together we designed the initial architecture. After that, people came and went, but I stayed. Over the years I became the developer who knew the whole system and steered its architecture. I worked on nearly every part of it: subscription provisioning to the network, an event-processing system with guaranteed delivery and automatic retries, billing, integrations with dozens of legacy backend systems, the internal customer-service tool and the customer-facing mobile app.

• Node.js
• TypeScript
• React
• React Native

Kesko — Caara Leasing

I was a developer in a team of up to four that built a mobile app and its backend services from start to finish for Caara Leasing, the car-leasing service of the Finnish retail group Kesko. After that, another developer and I built the Android version of Kesko’s Volkswagen Owner app, based on the existing iOS app.

• TypeScript
• Node.js
• React Native
• Android

OP — Osta laskulla

I was the architect and a developer on the Osta laskulla (“Buy with invoice”) payment button for OP, Finland’s largest financial group. It lets online shoppers pay by invoice or in instalments. We built the backend in Java and Kotlin and the purchase-flow UI in React. The hardest part was fitting the bank’s backend systems into a smooth checkout experience.

• Java
• Kotlin
• React

Fintoto backend systems

I developed backend systems in a small team for Fintoto, the Finnish horse-race betting operator. The most demanding part was a distributed bet-prioritisation service (Scala, Hazelcast) that I designed and built with another developer. It collected bets from several servers into a shared queue and fed them to the backend systems at a controlled rate. That way every user’s bets were handled fairly, and the backends were never overloaded. I also built internal tools and worked on Fintoto’s betting website.

• Scala
• Hazelcast
• Java

Fintoto Toto-mobiili

I designed the architecture and built most of Fintoto’s Toto-mobiili. The browser-based HTML5 service let users place bets, follow results and watch live Toto-TV broadcasts on every common smartphone of the time. It won Best HTML5 Consumer Service at Teleforum’s Best Mobile Service in Finland 2013 awards.

• JavaScript

OP file transfer service

I was team lead and a developer when we built a file-transfer service for small businesses in OP’s online bank. I coordinated the team’s work and the changes needed across the bank’s systems, and built the service together with the rest of the team.

• Java
• Spring

OP-Mobiili and S-Pankki Mobiili

I worked as a developer on the Android versions of two different banks’ mobile banking apps: for longer on OP-Mobiili, and briefly on S-Pankki Mobiili. On OP-Mobiili, I fixed critical barcode-scanning problems late in the project.

• Android