Sergei Garcia
Mentor
(1 reviews)
US$10.00
For every 15 mins
1
Sessions/Jobs
ABOUT ME
Ex-Reddit Web Lead | JavaScript, React, TypeScript & AI Mentor
Ex-Reddit Web Lead | JavaScript, React, TypeScript & AI Mentor
Hi, I'm Sergei. I help developers debug difficult JavaScript problems, build better React and Vue apps, improve web performance, and use AI coding tools with confidence.
I'm a senior software engineer and former web lead for Reddit's translations team, with 12+ years building web products. My experience spans React, TypeScript, Vue/Nuxt, Next.js, Node.js, GraphQL, server-side rendering, design systems, accessibility and automated testing. I bring a design background to engineering, so I care about how an application feels as much as how its code works.
At Reddit, I owned the web translation experience supporting 40+ countries and 20+ languages. I designed a move from browser-heavy translation logic to server-owned state, tested the approach through a controlled experiment, built Playwright coverage and developer tools, and created AI-assisted review and real-browser verification workflows. Previously, I led Typing.com's migration from Backbone.js to React and a shared component library. Through Toptal, I've built interfaces for St. Jude Children's Research Hospital, Northeastern University and AI product teams.
Teaching has been a constant throughout my career. At Thinkful, I mentored full-stack students one to one and taught 10+ workshops on JavaScript debugging, browser performance, web design and full-stack development, with an average workshop rating of 9.5/10 and 100% student satisfaction for mentoring. I've also taught bootcamp courses, coached engineers, onboarded teammates and conducted technical interviews at Karat.
I can help you with:
• JavaScript and TypeScript debugging, async behavior and maintainable code
• React, Next.js, Vue and Nuxt architecture, components and data fetching
• Node.js, Express, Apollo and GraphQL integration
• Chrome DevTools, rendering performance, network bottlenecks and bundle size
• Responsive CSS, accessibility and design systems
• Playwright testing, code reviews and gradual legacy migrations
• AI coding workflows: useful context, clear specs, review and verification
• Portfolio projects, technical interview practice and growing as an engineer
My approach is patient, practical and collaborative. We'll work through your actual problem, explain the reasoning behind the fix, and leave you with steps you can use independently. Whether you're learning the fundamentals or making a difficult architecture decision, I'll meet you where you are.
See my work and case studies at https://sergeigarcia.com. Share your goal, stack and what you've tried so far so we can focus the session on what will help most.
Spanish, English
Dublin (+01:00)
Joined October 2019
EXPERTISE
12 years experience
JavaScript has been the core of my professional work since 2014, from responsive websites and hybrid mobile apps to large React, Vue and ...
JavaScript has been the core of my professional work since 2014, from responsive websites and hybrid mobile apps to large React, Vue and Node.js applications. I've worked on products for Reddit, Typing.com, Expedia and healthcare clients, and taught JavaScript in bootcamps and one-to-one mentoring.
I can help you understand closures, scope, prototypes, this, promises and async/await; trace difficult bugs in Chrome DevTools; improve application structure; and refactor code without losing behavior. My goal is to make the reasoning clear so you can solve the next problem yourself.
9 years experience
I've built React products since 2017, including Expedia's advertising platform, a HomeAway MVP, Typing.com's teacher portal and customer-...
I've built React products since 2017, including Expedia's advertising platform, a HomeAway MVP, Typing.com's teacher portal and customer-service dashboard, and AI product interfaces through Toptal. As Lead Frontend Engineer at Typing.com, I led the migration from Backbone.js to React and built a shared Storybook component library.
I can help with component design, Hooks, state management, TanStack/React Query, API integration, rendering bugs, accessible UI and gradual migrations. We'll choose patterns that fit your app and make the trade-offs easy to understand.
12 years experience
Web performance has been part of my work since my early roles at Accenture and Inflection Point Systems. At Reddit, I investigated browse...
Web performance has been part of my work since my early roles at Accenture and Inflection Point Systems. At Reddit, I investigated browser translation overhead, designed a move toward server-owned state and ran a controlled experiment to validate the approach.
I can help you use Chrome DevTools to separate rendering, JavaScript, network and loading problems; reduce unnecessary code; find expensive updates; and improve asset loading and layout stability. I focus on measuring the bottleneck, making a targeted change and checking that the user experience actually improves.
9 years experience | 1 endorsement
I've used Node.js for full-stack products since 2017, including React/Express features for Expedia, a Hapi.js GraphQL server for HomeAway...
I've used Node.js for full-stack products since 2017, including React/Express features for Expedia, a Hapi.js GraphQL server for HomeAway, and GraphQL resolvers for Intelius and RxVantage. I also mentored students through the MongoDB, Express, React and Node.js stack at Thinkful.
I can help with API design, Express middleware, async control flow, error handling, authentication flows, GraphQL integration and debugging the boundary between browser and server. We'll work toward code that is understandable and testable.
7 years experience
I've used Vue and Nuxt in production work since 2019, leading the Intelius checkout flow and RxVantage healthcare front end, and later bu...
I've used Vue and Nuxt in production work since 2019, leading the Intelius checkout flow and RxVantage healthcare front end, and later building St. Jude Cloud's website rebuild with Vue 3, Nuxt 3 and Tailwind. That rebuild included a reusable design system, JSON-driven content and accessibility and performance checks.
I can help with Vue reactivity, component composition, Nuxt rendering, Apollo/GraphQL integration, forms, responsive interfaces and migration decisions. I explain the underlying model so debugging feels less like trial and error.
12 years experience
I've built responsive web interfaces throughout my career and taught HTML, CSS and web design at Thinkful and Desafio Latam. My work incl...
I've built responsive web interfaces throughout my career and taught HTML, CSS and web design at Thinkful and Desafio Latam. My work includes design systems for Typing.com and St. Jude Cloud, translating Figma designs into reusable components and improving accessibility.
I can help with semantic HTML, Flexbox and Grid, responsive layouts, Tailwind, CSS debugging, keyboard interaction, contrast and practical screen-reader checks. We'll aim for an interface that is clear, maintainable and usable on different devices.
4 years experience
I use TypeScript in production front ends, developer tools and large web codebases, including Reddit's translation experience and React/N...
I use TypeScript in production front ends, developer tools and large web codebases, including Reddit's translation experience and React/Next.js projects through Toptal.
I can help you model component props and API responses, narrow unions safely, understand generics, debug compiler errors and introduce types gradually. I favor types that clarify how the program works and catch useful mistakes without making everyday changes unnecessarily complicated.
REVIEWS FROM CLIENTS
(1 reviews)
Casper Warnich
October 2019
Very understanding of the problem and has a ton of experience and sample projects. Sergeis English is also very good. Can only recommend.
SOCIAL PRESENCE
2314 Reputation
7
26
47
EMPLOYMENTS
Senior Software Engineer / Web Lead, Translations
Reddit, Inc.
2023-11-01-2026-09-01
- Web lead for Reddit's translations team throughout my tenure, owning the web experience for translated posts and comments across 40+ co...
- Web lead for Reddit's translations team throughout my tenure, owning the web experience for translated posts and comments across 40+ countries and 20+ languages. Set technical direction, planned delivery and onboarded front-end engineers.
- Redesigned translation indicators, language controls, translated/original text switching, compact views, feedback dialogs and settings.
- Designed a move from browser-heavy translation logic toward server-owned state and lazy loading. Set up and ran a controlled experiment that validated performance improvements and informed the team's roadmap.
- Built server-rendered features, GraphQL integration, request middleware and server-to-client data flow, and wrote BigQuery SQL to measure results.
- Created Playwright end-to-end coverage for translated content across post pages, feeds and search.
- Built and released internal VS Code and Chrome DevTools extensions for targeted tests, debugger setup, experiment reproduction, GraphQL inspection and sharing working debug configurations.
- Created domain-aware AI review prompts, quality checks and real-browser verification runbooks to make AI-assisted changes easier to trust.
- Consolidated localization knowledge into a runbook and built an agent workflow the team used to deploy new languages.
- Wrote onboarding and domain guides, a practical AI course for colleagues, and short decision documents to align engineering and product teams.
SQL
TypeScript
Google BigQuery
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SQL
TypeScript
Google BigQuery
React
Codex
JavaScript
Mentoring
GraphQL
Performance Optimization
Mcp
Playwright
Llm agents
Claude code
Agentic system design
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Freelance Software Engineer (part-time)
Toptal
2023-09-01-2025-11-01
Part-time freelance front-end engineering through Toptal for research organizations and AI product teams.
- St. Jude Children's Research...
Part-time freelance front-end engineering through Toptal for research organizations and AI product teams.
- St. Jude Children's Research Hospital (2025): sole front-end engineer across three projects. Built the St. Jude Cloud website rebuild with Vue, Nuxt and Tailwind, a Figma-based design system, JSON-driven page rendering, generated content pages, filtering and pagination. Ran screen-reader, contrast and Lighthouse checks. Rebuilt Sprocket's website and documentation theme, and LearnGenomics.dev with Next.js and MDX. The rebuilds were completed, but the hospital has not launched them.
- Northeastern University, College of Engineering (2023–2024): built a React, TypeScript and Tailwind AI product-research interface for footwear and apparel brands, including sentiment dashboards, concept evaluation and a ChatGPT-powered assistant. Set up AWS S3 hosting and organized planning for an MVP demo deadline.
- Marmalade (2024): delivered Next.js, TypeScript, Tailwind and Apollo GraphQL components, banners and layout redesigns for an AI-driven independent-brand discovery platform.
- AquascapeAI (2024): built an AI aquarium-design generator front end from scratch with Astro, React, Tailwind and Vercel, including reusable keyboard-accessible form components.
Amazon S3
TypeScript
Accessibility
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Amazon S3
TypeScript
Accessibility
React
GraphQL
Next.js
Nuxt.js
Figma
Tailwind css
Vue.js
Astro.js
Llm agents
Claude code
View more
Lead Frontend Engineer
Teaching.com
2021-01-01-2023-10-01
- Led modernization of Typing.com's teacher portal and internal customer-service dashboard, replacing Backbone.js front ends with React w...
- Led modernization of Typing.com's teacher portal and internal customer-service dashboard, replacing Backbone.js front ends with React while retaining the existing PHP/Laravel backend.
- Started with the smaller support dashboard, then led the teacher portal rewrite. Mounted the new React application inside existing Laravel pages to keep migration risk manageable.
- Chose React Query for server-state fetching and caching, and simplified the architecture when an early approach proved too complex.
- Built a shared Storybook design-system library from Figma designs, using Tailwind, Headless UI and Chakra UI.
- Introduced a PR process, issue triage, accessibility linting, pre-commit checks and Storybook interaction tests.
- Developed a GraphQL architecture proposal with a working demo and risk analysis.
- Used Shape Up to turn stakeholder requests into manageable work and gave weekly demos to explain decisions and delivery challenges.
- Mentored a front-end developer and a designer/developer, and worked through architecture trade-offs with leadership to agree on a practical direction.
Node.js
Backbone.js
React
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Node.js
Backbone.js
React
Redux
GraphQL
Design Systems
Tailwind css
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PROJECTS
Reddit web translations: performance, testing and AI workflowsView Project
Reddit
2026
As web lead for Reddit's translations team (2023–2026), I owned the web experience for translated posts and comments across 40+ countries...
As web lead for Reddit's translations team (2023–2026), I owned the web experience for translated posts and comments across 40+ countries and 20+ languages. I designed a move toward server-owned translation state and lazy loading, and ran a controlled experiment to validate the approach. I also built Playwright coverage, domain-aware AI review and real-browser verification workflows, and an agent workflow used for language launches.
The public case study explains my architecture decisions, delivery approach and lessons in performance and verification. Internal code is not public.
TypeScript
GraphQL
Performance Optimization
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TypeScript
GraphQL
Performance Optimization
Playwright
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Typing.com: gradual migration from Backbone.js to ReactView Project
Teaching.com / Typing.com
2023
As Lead Frontend Engineer (2021–2023), led modernization of Typing.com's customer-service dashboard and teacher portal. Replaced Backbone...
As Lead Frontend Engineer (2021–2023), led modernization of Typing.com's customer-service dashboard and teacher portal. Replaced Backbone.js front ends with React inside the existing Laravel application, avoiding a big-bang backend replacement.
Used React Query for server state and built a shared Storybook component library with Tailwind, Headless UI and Chakra UI. Added review standards, accessibility linting and interaction tests, and mentored engineers through architecture decisions and delivery.
React
Storybook
Design Systems
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React
Storybook
Design Systems
Tailwind css
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