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JK

Ideas, shipped. Not someday.

Jakub Kołosowski

Senior software engineer and team lead — building high-scale web apps and leading the people who ship them.

Since 2020

I think like a product owner and build like an engineer: frontends that stay fast at scale, services that hold up under load, and a team that keeps shipping.

Tools I reach for

Frontends that feel effortless

Web apps, dashboards and mobile — accessible, fast, and calm under load.

  • React
  • Next.js
  • TypeScript
  • JavaScript
  • HTML
  • CSS
  • Tailwind CSS
  • Redux
  • Zustand
  • TanStack
  • D3.js
  • React Native

Backends that scale on demand

Event-driven services on AWS Lambda with real-time data behind high-traffic products.

  • Node.js
  • Python
  • Bash
  • AWS
  • DynamoDB
  • PostgreSQL
  • Azure
  • Terraform
  • REST APIs
  • OpenAPI
  • WebSockets
  • CI/CD

Shipping with AI in the loop

AI wired into the product and the workflow — prompts, agents and evals that hold up.

  • Claude
  • ChatGPT
  • Codex
  • OpenRouter
  • GitHub Copilot
  • Microsoft Foundry
  • Prompt engineering

Correctness that pays the bills

80%+ coverage on fintech and ticketing — the systems where bugs cost money.

  • Jest
  • Playwright
  • Vitest
  • Cypress
  • Cucumber
  • React Testing Library

How the team stays fast

Leading small teams, reviewing every PR, mentoring — delivery you can predict.

  • Team leadership
  • Architecture
  • Code review
  • Scrum / Agile
  • Git
  • Figma
  • Jira
  • Storybook

Recent work

What people say

Jakub has deep expertise in web application development, particularly with React and TypeScript, and has also demonstrated strong end-to-end capabilities across the full stack.
Engineering Manager
Jakub is highly productive, self-directed, and always willing to jump in and help others — he brings a thoughtful, solutions-focused mindset to every project.
Senior Full-Stack Engineer
Combines strong technical skills with a great sense of UX/UI, resulting in clean, user-friendly interfaces — he solves problems independently and is always open to collaboration.
QA Engineer
His commitment to self-development and eagerness to learn have enabled him to become an experienced full-stack developer in a very short period of time.
IT Project Manager
He's a great team player — reliable, communicative, and always willing to lend a hand or share knowledge.
Frontend Developer
One of the most talented developers I've had the pleasure of working with — a great work ethic, very skilled, with an eye for design.
Senior Product Manager

Hi, I'm Jakub

I'm a Senior Software Engineer and Team Lead with six-plus years building high-scale web apps, focused on React, Next.js and TypeScript.

I lead frontend teams, ship reliable product features, and run AI-assisted workflows with Claude and Codex to push delivery speed and code quality — without trading away correctness on the systems where bugs cost money.

Outside product work I design and build landing pages end to end — visual direction, layout and copy flow, then scroll-driven motion that makes the story land.

Role
Senior Engineer & Team Lead
Experience
6+ years
Base
Poland, remote-friendly
Focus
React · Next.js · TypeScript · Node.js · AI
Also
Landing page design & motion