Simon Lumikello

Profile

Software engineer with 15+ years of experience building Valmet IQ Machine Vision, a quality inspection system for the pulp, paper, board and tissue industries.

Tens of languages, tools and technologies
Dozens of software modules with hundreds of thousands of LOC
Hundreds of installations worldwide, supported and extended with new features
Countless features and several sub-products built from scratch

I started as a UI developer, then moved to full stack, and led UI and API development for the last decade. Most recently, as architect and lead developer, I replaced the product’s legacy desktop UI with a modern web app built from scratch on React, OpenAPI and .NET, and took it from proof of concept to dozens of shipped systems. More on that in the timeline below.

I also set up and optimized development workflows, tooling and infrastructure, helped hire and onboard new developers, and worked closely with project engineers in the field. I’ve seen subcontracting from both sides: as a subcontractor for Metso early on, and later leading subcontracted developers for Valmet.

My main tech stack is TypeScript, React, OpenAPI and .NET, and in my hobby projects I use Next.js, Supabase, Flutter and Vercel. Over the years I’ve worked through several generations of web and desktop tech, from ActionScript in Macromedia Flash (the good old days), PHP and Java Swing to Electron, SignalR and Plotly.js, and built and released several Android apps.

I’ve been building software since long before AI coding tools, but I’ve recently switched to an AI-first workflow, using Kiro, Antigravity, Codex or Claude Code depending on the project. At Valmet I brought a coding agent into the team’s development process, and in my own projects an idea now becomes a working prototype in a day and a polished app within a week, where it used to take weeks.

Expertise

Frontend: TypeScript, React, Next.js, Material UI, TanStack Query, Zustand, React Router, Zod, Tailwind CSS, Electron, i18n
Data visualization: Plotly.js, Recharts, MUI X Charts, Real-time and large datasets
Backend: C#, .NET, ASP.NET Core, OpenAPI, openapi-generator, EF Core, Dapper, SignalR, MSSQL, T-SQL, Supabase
Design & architecture: Software architecture, REST API design, Database schema design, UX design
Tooling & testing: Git, Bun, Vite, Biome, Playwright, Cypress
CI/CD & infrastructure: Jenkins, GitLab CI, TeamCity, Vercel, MAAS
Mobile: Flutter, React Native, Android
AI: Claude Code, Codex, Antigravity, Kiro, Agent workflows (rules, skills, hooks, MCP integration)
Team tools: GitHub, Bitbucket, Jira, Confluence
Team & process: Team leadership, Hiring and mentoring, Code reviews, Roadmapping and prioritization, Kanban, Process and workflow design, Stakeholder communication, Field support, Technical documentation
Earlier: Java, PHP, Vue

Timeline

2012–2026

Valmet Automation, formerly Metso Automation

2024–2026 · Jyväskylä

Chief software design engineerpromotion

Led team-wide workflows and tooling, hiring and mentoring, and brought AI into the development process.

Designed the team’s Jira setup (issue types, fields, workflows) and drove its rollout.
Moved issue reporting from chat to Jira: trained project engineers on the workflow and why it pays off, and configured Rovo to raise ticket quality.
Connected Kiro to Valmet’s internal MCP servers, cutting Jira ticket handling time from hours to tens of minutes.
Kept the tech stack current across several major versions of .NET and React.
Migrated the UI’s end-to-end tests from Cypress to Playwright.

New technologies: Kiro, Rovo, Playwright

2023–2024 · Jyväskylä

Senior software design engineerpromotion

Technical owner of the product’s UI, making decisions on feature design, implementation and roadmap.

Took the UI into production, both as upgrades of existing systems and in new installations.
Handled feedback from the field as the UI started shipping to customers, supporting project engineers and customers both remotely and on site.
Automated user documentation as part of the build, from screenshots to localized PDF manuals.

2020–2023 · Jyväskylä

Software design engineer

Architect and lead developer of the product’s new UI, managing the subcontracted developers on the project.

Brought the new web app to feature parity with the legacy UI: for each feature, studied how it was used, decided what to keep, drop or improve and with which technology, then prioritized and built it.
Took ownership of the team’s CI/CD, first for the UI and later for the whole product.
Improved the UI’s Cypress end-to-end test setup and extended its coverage.

New technologies: Plotly.js, Electron, Material UI, SQLite, Bitbucket, Git, Linux, Cypress

2017–2019 · Tampere

Software design engineer

Moved to Tampere to focus on research: investigated new technologies, pitched feature improvements and built prototypes.

In late 2018, proposed rebuilding the product’s legacy desktop UI as a web app, ran the technology evaluation and designed its full-stack architecture: React and TypeScript frontend, .NET backend, cleanly separated from the existing system it integrates with.
Designed it for the long run from day one: a contract-first API with OpenAPI and code generation, backward compatibility with installations of different ages, CI, an installer and automated upgrades.
Set priorities and documented the architecture, aligning engineers and stakeholders on design decisions.

New technologies: Node.js, React, TypeScript, OpenAPI/Swagger, Vue, Semantic UI, ASP.NET Core, npm, yarn, Webpack, Jest, Docker

2012–2017 · Jyväskylä

Software design engineer

Continued development of the Metso PQV user interface after being hired directly by Metso Automation in Jyväskylä.

Migrated the UI from web pages and Java applets to a self-contained Java desktop application.
Removed obsolete components and set up build tooling, code signing and CI for the new application.
Supported deployed installations with bug fixes, new features and performance improvements.

Technologies: Java, .NET, C#, PHP, JavaScript, MSSQL, SVN, Jira, Confluence, Jenkins

2010–2012

Petrozavodsk State University IT park

2010–2012 · Petrozavodsk

Software developer

As a subcontractor for Metso Automation, maintained and improved the user interface of Metso PQV (Process and Quality Vision), an integrated web monitoring and quality inspection system.