Kai Sellgren

Demo Project|Talent AI Search Engine (Vertex AI)

A platform that connects sales people and talents. Features an AI-powered search that uses LLM agents to triage, find, rank and summarize talents.

Hosted on Google Cloud: https://talents-iqgi7ee7uq-ey.a.run.app/
GitHub source code: https://github.com/kaisellgren/talents

Studied and learned to do AI engineering to better understand how to utilize AI agents for real-life business use cases.

Implemented a multi-agent architecture with agent orchestration:
Triage agent: classifies intent by figuring out what is needed & what requirements are
Research agent: integrates to an external PostgreSQL database for matching talents
Ranking agent: determines the ranking/order of talents
Summarizer agent: writes out detailed summaries for each talent ("why is this talent a good match")

Implemented Google Cloud infra and deployment pipeline.

OP Corporate Bank|OP Lasku

An e-commerce payment method for customers of any Finnish bank. Similar to Klarna payments. This is available in hundreds of Finland's e-commerce stores.

I was one of the core technical owners of the service from day one, wearing whatever hat was needed. I worked on architecture, development, testing, cloud infrastructure, operations and stakeholder collaboration.

On the architecture side, I focused on building a resilient, production-grade system. I designed the APIs, handled the database modeling and implemented patterns like circuit breakers and distributing tracing to ensure we actually had visibility when things went south. I paid a lot of attention to data consistency and transactions to ensure data validity without forgetting GDPR compliance.

I took ownership of our AWS infrastructure: treating everything as code using AWS CDK to manage our networking, load balancing, firewalls, database, CDN, container and CI/CD pipelines.

As a full-stack engineer, I was just as comfortable working in the codebase as I was provisioning servers. I built our backend APIs, handled session management and developed React frontends. I had to pay special attention to accessibility and screen readers. To keep production deployments stress-free, I built a parallelized automated testing suite that ran thousands of tests across unit, integration and E2E layers.

Beyond this, I ran and evolved the production system for years. I helped to resolve police investigations related to payment fraud and over several years, managed to keep the service always-on with only a single planned downtime - an achievement I'm proud of.

OP Corporate Bank|AWS Platform and Delivery Automation

Enablement of cloud infrastructure and deployment practices supporting several OP Corporate Bank's applications and our development team.

I designed and implemented AWS infrastructure and deployment processes that improved delivery reliability and reduced manual labor massively.

I introduced and maintained CI/CD pipelines, automated operational tasks and improved the developer experience and demanded higher operational maturity from the team. DevOps became the new norm.

I also helped to create a fully automated testing environment in terms of infra and day-to-day developer practices.

OP Corporate Bank|OP's online financing service

A platform to easily manage hire-purchase financing, one-off loans, overdraft facilities and OP Lasku.

You can view your financing agreement details and invoices. Make requests for a change in the financing agreement. Determine outstanding debt for the current day. Apply for an authorization to take a motor vehicle abroad.

Corporate customers can manage their investment financing.

I was with this service from day one, which meant doing a bit of everything: architecture, writing code, setting up infrastructure and talking with business representatives to figure out what we actually needed to build.

When designing the system, my main goal was making sure it wouldn't fall over and that we'd actually know why if it did. I handled the database design and set up distributed tracing so we weren't running blind in production. A huge chunk of my time went into learning BanqSoft View21 ledger system inside out so I could deeply bake it into our platform. That integration handled all our invoicing, accounting, and payment schedules. On top of that, I built an asset management system from scratch for corporate clients who needed to track massive fleets of vehicles and machinery.

I also looked after our AWS setup. I didn't want to click around in the console, so I used AWS CDK to manage absolutely everything as code: networking, firewalls, databases, containers, and the CI/CD pipelines.

I've always worked across the whole stack. I wrote the backend services and ledger logic, but I also built the React frontends, where I spent a lot of time making sure everything was fully accessible and worked well with screen readers. To make sure deployments were a success, I built a test suite that ran hundreds of unit, integration, and E2E tests in parallel so we got fast feedback.

I ended up running and scaling this system for years. Between writing new features, I was hands-on with fixing tricky customer issues in tight communication with stakeholders, and I'm proud that we kept the platform highly stable and accessible to users with disabilities the entire time.

OP Corporate Bank|OP Vendor Finance

A highly specialized sales finance ecosystem designed for point-of-sale merchants allowing partnering businesses to provide credit directly for big-ticket purchases.

I engineered solutions ranging from paperless electronic signing capabilities to the design and implementation of customer-facing APIs used by over a thousand client organizations. My responsibilities spanned backend and frontend development, integration work and long-term production support for business-critical services.

I also helped to create a tablet-friendly UI for Puustelli and a complex multi-language contract PDF generation system.

OP Corporate Bank|Git version control

Replacing existing source version control (SVN) with Git.

The customer previously relied on dated SVN to handle source code versioning. I was the first to propose Git and I pushed for it and our team pioneered it within the organization. Years later mostly every team had migrated to Git.