Large-scale modernization
I can help you plan and execute zero-downtime migrations — replacing dependencies, moving data, and modernizing legacy systems without disrupting operations.
Senior Rails Developer | Consultant • Remote
Kai Hofius
I build reliable, modern web systems focused on performance, maintainability, and developer effectiveness. I work across domains with deep Rails roots and 12 years of engineering experience behind me. When I'm not coding, I'm usually playing music with friends, spending time with my dog, or investing in my community.
Open to full-time roles and contract engagements.
Practical collaboration
Delivering work that pairs Rails product velocity with real engineering discipline, from architecture to deployment and developer experience.
Performance & reliability
I can identify and fix performance bottlenecks (slow queries, N+1 issues, inefficient rendering) and build systems that hold up as they grow.
Developer experience
I can help your team move faster: improving onboarding, documentation, test hygiene, and code review practices to make engineering more effective and delivery more predictable.
Full-stack delivery
I contribute at any layer of a production system — backend, frontend, data — and pick up new tools when the work calls for it.
Selected experience
Binti
Senior Software Engineer • January 2021 - May 2026
- Led a zero-downtime migration of file upload management from Refile to Shrine across millions of records, adding validation, deduplication, and metadata preservation.
- Cut page load times from 30s to 2s by fixing N+1 queries, adding indexes, and optimizing endpoints.
- Shipped key features including Permanency Planning and Payments Reporting with Rails and React/GraphQL.
- Mentored engineers through code review, pair programming, and architectural discussion.
Informed K12
Full-Stack Software Engineer • August 2016 - November 2020
- Built form automation tools used by educators and administrators to collect, route, and approve digital documents across dozens of school districts.
- Improved developer experience through documentation, test hygiene, and PR practices, accelerating delivery and onboarding.
- Mentored junior engineers through 1:1 guidance, code review, and architectural reasoning.
Earnest
Software Engineer • May 2014 - July 2016
- Built an automated withdrawal and deposit system that scaled collections and disbursements from dozens to thousands of clients.
- Implemented Payment Flexibility tooling to model loan schedule changes and their effect on interest accrual and amortization.
Skills
Core focus
Ruby on Rails • Full-stack web systems
Languages
Ruby • JavaScript (ES6+) • SQL
Frameworks
Rails • React • GraphQL
Databases & infra
PostgreSQL • Sidekiq • Redis • GCP
Practices
CI/CD • Test Automation • Feature Flags • Code Review
