# Yaroslav Pakhaliuk

> Senior Software Engineer, ex-Wix. Also known as Yarik Leto. Based in Bangkok, Thailand; open to relocation.

Canonical page: https://yarik-leto.com/ · Last updated: 2026-11-15 · This file mirrors the page; the page is the source of truth.

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Senior Full-Stack Engineer with 5+ years on Wix's Server Infrastructure team, building the internal tools 1,000+ engineers used to run and debug serverless apps: the web app they managed their apps in, a local run mode for the platform CLI, and gRPC streaming. More recently, built a Slack support agent that answered 60%+ of developer questions on its own, and an AI pull-request reviewer. Works AI-first with coding agents (Claude Code, OpenAI Codex, Cursor) and publishes open-source tools. Before Wix, at MEGOGO, was the first to bring React to the Smart TV app, used by millions of viewers, leading its move off a hand-written vanilla JavaScript UI, which cut frontend hiring time from months to about a week. Earlier: products in fintech, healthcare data and consumer web; has led frontend architecture, interviewed candidates and mentored engineers.

Industries: developer platforms (SaaS), video streaming, fintech, healthcare data, e-commerce.

## Contact

- [Email](mailto:hi@yarik-leto.com): hi@yarik-leto.com
- [LinkedIn](https://www.linkedin.com/in/yarik-leto)
- [GitHub](https://github.com/yarikleto)
- [Website](https://yarik-leto.com/)
- [Resume (PDF)](https://yarik-leto.com/yaroslav-pakhaliuk-resume.pdf)

## Experience

### Senior Full-Stack Engineer, Server Infrastructure - Wix
Dec 2020 - May 2026 · Kyiv, Ukraine (Hybrid)

- Designed and built the web app (React, TypeScript, JavaScript, HTML/CSS) that Wix developers used to manage their backend apps: nearly all day-to-day management of 1,000+ apps ran through it. Owned it end to end, UI and UX included, for 2.5 years, and received formal internal recognition for its developer-experience impact.
- More recently, built an LLM support agent in Slack and an AI pull-request reviewer, grounded in internal docs, code and examples through a retrieval-augmented generation (RAG) pipeline, plus service logs. The agent answered 60%+ of developer support questions on its own, and together with a human covered about 95%, since it surfaced the relevant docs and logs.
- Took part in the team's developer-support rotation for the platform's 1,000+ apps: diagnosed failing services in Grafana (logs, metrics, traces) and resolved them hands-on in Kubernetes.
- Added a local run mode to the platform's Node.js CLI: apps now start locally in seconds instead of a minutes-long deploy to production, with production services mocked.
- Added gRPC streaming and Server-Sent Events (SSE) to the serverless runtime and its REST layer, a gap the underlying framework had left open for years; teams needing streaming for LLM features no longer had to switch frameworks.
- Designed type-safe indexing and query APIs for AWS DynamoDB (NoSQL), including custom indexes and queries across multiple indexes.

### Senior Front-end Engineer - MEGOGO
Aug 2019 - Jul 2020 · Kyiv, Ukraine

- Led the Smart TV app's move from a hand-written vanilla JS UI to React, designing the architecture for the memory, CPU and rendering limits of low-end TVs (Pixi.js, WebGL and Canvas 2D where the DOM was too slow). Frontend hiring time fell from months to about a week: engineers who could build for TVs were rare, React developers were not.
- Built an in-app performance probe that measured, unnoticed by viewers, how the app ran on customers' own TVs. Before, nobody knew which of the millions of viewers would get a laggy UI, a revenue risk; the data let the team ship UI that stayed smooth even on the lowest-end devices.
- Interviewed frontend candidates in a format they repeatedly praised, which helped win strong engineers in a tight hiring market; mentored junior engineers through onboarding, code review and delivery.

### Senior Front-end Engineer - Finotec Asia Corp
Apr 2019 - Aug 2019 · Remote

- Led frontend architecture and implementation decisions as technical owner of a React and TypeScript fintech product.
- Improved code quality through refactoring, code reviews and shared engineering standards; mentored junior engineers through onboarding and feature delivery.

### Front-end Engineer - HHS Technology Group
Oct 2018 - Feb 2019 · Kyiv, Ukraine

- Built a sports match administration web application from scratch in React and Sass.
- Refactored legacy frontend code on a healthcare data platform, fixing memory leaks and improving performance; delivered investor-demo features for a funding round on a tight deadline.

### Full-Stack Engineer - SaveFrom.net
Jun 2018 - Aug 2018 · Remote

- Implemented geolocation-based routing, affiliate integrations and contextual monetization logic across frontend and backend of a high-traffic consumer web product.

### Full-Stack Engineer - TulaCo
Dec 2017 - May 2018 · Remote

### Front-end Engineer - MASS Group
Sep 2017 - Nov 2017 · Remote

### Full-Stack Engineer - ART-WEB
Feb 2017 - Apr 2017 · Simferopol, Ukraine

- Built and maintained e-commerce sites on a CMS with Sass and Gulp: new features, bug fixes and client support.

## Projects

### CS:GO Club - community platform
Oct 2026 - Present · https://csgo-club.alfimois.workers.dev/

- Volunteer: built and run the platform for a 60+ person community's Friday CS:GO nights, in TypeScript, React, Cloudflare Workers, SQL (D1) and Python. Game servers start on demand and are deleted after each session, so the club pays only for play time.

### Claude Teacher - Claude Code plugin
Mar 2026 - Present · https://github.com/yarikleto/claude-teacher-plugin

- Open-source AI tutor plugin in Python, JavaScript and Bash that teaches by guiding instead of answering, tracks what the learner knows and quizzes with spaced repetition; 15 GitHub stars.

### claude-profile - CLI
Mar 2026 - Present · https://github.com/yarikleto/claude-profile

- Open-source Bash CLI for macOS and Linux that switches between Claude Code configuration profiles, with Git-based profile history and a bats test suite run in GitHub Actions CI; 12 GitHub stars.

## Skills

- AI engineering: LLM applications, retrieval-augmented generation (RAG), AI agents, Model Context Protocol (MCP), agent plugins, skills and hooks, prompt engineering, AI-assisted development (Claude Code, OpenAI Codex, Cursor)
- Languages: TypeScript, JavaScript, Bash, HTML, CSS, Sass
- Backend and platform: Node.js, gRPC, Server-Sent Events (SSE), REST APIs, AWS DynamoDB, Apache Kafka, serverless, microservices, Grafana, platform engineering
- Frontend: React, Redux, Electron, Pixi.js, WebGL, Canvas 2D, Vite, web performance optimization
- Testing and delivery: GitHub Actions, CI/CD, Vitest, Playwright, bats, npm, Homebrew, code review, mentoring