Andrew Kozin

Moscow Institute of Physics and Technology (State University) (MIPT)

Master of Science - MS, Chemical Physics

July 1, 1987 – July 1, 1993

Evil Martians

Backend developer

October 1, 2015 – Present

Лисбоа, Португалия

Individual Business Solutions

IT Consultant

May 1, 2012 – September 1, 2014

Onside.io – European Apple Marketplace

May 1, 2024 – August 1, 2025

Stack: Rust, sqlx/PostgreSQL, Swift integration, Kubernetes Role: Rust Backend Engineer My favorite project to date. I finally got the chance to build a large production system from scratch in Rust — after years of learning the language through side-projects and experiments. This experience solidified Rust as my preferred tech stack for the future. I focused on backend architecture: PostgreSQL data modeling, authentication, billing and ledger systems, integrations with Apple Store Connect (a rather vague API), as well as app configuration and various web server APIs. Working with a fast-growing team and alongside former colleagues I deeply respect made this journey even more rewarding.

Yetto – Reactive Rails App

January 1, 2024 – April 1, 2024

Stack: Ruby on Rails, Turbo Streams, Next.js, PostgreSQL Role: Backend Engineer A small, experimental project with just two engineers and one designer on our side. We built complex reactive pages powered entirely by server-side Turbo Streams. Though the stack deviated from what I’d typically use in large-scale systems, it worked surprisingly well under constraints — both technical and organizational. It reminded me that practicality often trumps purity in real-world scenarios.

Tesote – Early-stage Fintech for LATAM

January 1, 2023 – October 1, 2023

Stack: Ruby on Rails, PostgreSQL Role: Backend Engineer I joined the team at an early stage to build customer onboarding flows and integrate with Latin American banks' APIs (some of which didn’t exist and had to be reverse-engineered). This was classic "move fast and fix later" engineering — the kind I enjoy for its creative chaos and architectural impact. My colleague later expanded the integration layer by building scrapers in absence of formal APIs.

Healthie – infrastructure for virtual-first healthcare

January 1, 2023 – January 1, 2023

Stack: Ruby on Rails, GraphQL, RSpec Role: Backend Engineer (Consultant) A short project with a narrow scope — to fix some problems in the GraphQL interface, provide heavy code refactoring and improve test coverage. This was the only project where I haven't had to deal with the data layer, neither touch the company's business domain.

Sera Systems – APIs for Home Services Platform

March 1, 2022 – January 1, 2023

Focused heavily on internal GraphQL APIs — more than on any previous project. Embedded directly in the client’s backend team, I had full ownership of a specific part of the system, contributing to both feature development and infrastructure.

Mojoflower – Blockchain-based ownership registry

September 1, 2021 – November 1, 2021

Stack: Go language, Blockchain-centered Role: Backend Engineer A short project where I should revive the pre-existing Go project and make it work. An interesting option to review and dig deeply into the mid-size codebase using this stack.

Chowbus – High-Scale Food Delivery Platform

May 1, 2021 – September 1, 2021

Stack: Ruby on Rails, GraphQL, PostgreSQL, Go, BoltDB Role: Backend Engineer (Client-Embedded) Worked on the billing system in a mature, high-load environment with strict reliability requirements. This project stood in contrast to early-stage startups — demanding careful coordination across multiple teams. Also my first exposure to Go in production. While it was educational, I ultimately prefer Rust for any performance-critical programming.

eBay for Business – Seller Management Tool

June 1, 2016 – March 1, 2021

Stack: Ruby on Rails, GraphQL, PostgreSQL, Redis, Kubernetes, and everything Role: Technical Lead Led development of a tool enabling merchants to manage listings across multiple eBay marketplaces and regions. Major challenges included multi-language UI (up to 14 languages) and real-time sync between eBay APIs, internal systems, and our frontend. I transitioned leadership twice during this multi-phase project — first taking over from the initial lead, then handing it off to the next. This period also deepened my PostgreSQL knowledge significantly and even turned me into the data-first person.

Elementaree – Subscription-Based Food Delivery

February 1, 2016 – July 1, 2016

Stack: Ruby on Rails, PostgreSQL, Redis Role: Backend Engineer Built core backend features including onboarding and payment integrations. This is also the project where the open-source gem dry-initializer was born — and it’s still in use today. Fun fact: I became a loyal customer and used the service for years while living in Moscow.