SergeiGarcia
Designer by eye, teacher by habit, engineer by trade.
Software Engineer · 13+ years
Based in Dublin, Ireland
I build fast, accessible websites and the tools that help teams ship them. I care how things look and feel, I love helping people get unstuck, and lately I'm exploring how far AI can take all of that.
- Developer tools
- Accessibility
- Web performance
- AI agent workflows
- Writer
- UX and motion
- Mentor
- Speaker
- Full stack
Work
Over 13 years of front-end and full-stack roles, from consulting to product teams.
Nov 2023 to Sep 2026
Reddit
Senior Software Engineer
Web lead for Reddit's translations team: owned the web experience for machine-translated posts across 40+ countries and 20+ languages, made it faster and built its tests, tools and AI workflows.
2023 to 2025
Toptal
Freelance Software Engineer
Freelance front end work through Toptal for research and product teams, including St. Jude Children's Research Hospital, a university and two AI product startups.
Jan 2021 to Oct 2023
Teaching.com / Typing.com
Lead Frontend Engineer
Led Typing.com's move from Backbone to React for its teacher portal and customer service dashboard, on a platform with 35M+ monthly users, plus a shared component library and mentoring.
Jun 2021 to Feb 2022
Karat
Interview Engineer
Ran technical interviews for hiring teams, with a focus on fair, consistent assessment and a constructive experience for candidates.
Kind words
From managers, teammates and people I mentored.
I've met few engineers who've had that invaluable knack of making the people around them better, but Sergei is one of them. When we talk about 10x engineers, that's what we really mean…
Daniel MerrimanProduct Lead, Government Digital Service (UK)Managed Sergei at Teaching.com, 2023 …he proved to be one of the best FE engineers I've ever worked with, and a very proactive and knowledge hungry person.
Juan Pablo Lozano GómezStaff Software Engineer, RedditManaged Sergei at Reddit, 2026 This man is THE best mentor I've ever had and I'm probably 20 years his senior.
Bryan SpearmanWeb Developer III, BlueCross BlueShield of South CarolinaMentored by Sergei at Thinkful, 2019
Projects
Case studies: the problem, what I owned, the decisions and what changed.
Nov 2023 to Sep 2026
Breaking Reddit's language barrier with AI translation
As web lead for Reddit's translations team, I moved translation work to the server for speed, automated language launches with AI agents and built real-browser checks for AI changes.
- Web performance
- Server-side rendering
- AI agent workflows
- TypeScript
- A/B testing
2024 to 2026
Tools that make the whole team faster
When I spot daily friction for my teammates, I build the tool that removes it. A VS Code extension and a Chrome DevTools extension, both started without being asked.
- TypeScript
- VS Code Extension API
- Chrome extensions
- Vite
- Vitest
2026 to now
The Agents workspace
A plain-text, git-tracked system for running AI agents: shared memory, a local search engine, cheap workers with strong checks, and rules enforced by code.
- AI agents
- Agent orchestration
- LLM evals
- Observability
- Python
2021 to 2023
Typing.com React rewrite
Led the move of Typing.com's teacher tools from Backbone.js to React, with a shared component library and quality checks built in.
- React
- TanStack Query
- Storybook
- Chakra UI
- Tailwind CSS
Writing
How I work with AI agents, build front ends and keep teams moving.
My agents' search reads 25 times less to find one fact
How my agents' local search works, part by part, and what it saves. On 28 questions it read about 25 times less text than rg plus whole files. With a real agent, the gap was much smaller.
- AI agents
- Information retrieval
- Embeddings
- Context engineering
Don't send a whole agent to answer a yes or no question
I asked a decision model and two AI agents the same ten questions about 40 job postings. Quality was a near tie. The decision model was 10 to 41 times cheaper and about 16 to 22 times faster.
- AI agents
- Decision models
- LLM evals
- Cost optimization
Done is a claim. A passing check is a fact.
What a check is, what makes a good one, and two real cases: moving 10,656 links without breaking one, and tailoring a resume without inventing a fact.
- AI agents
- Verification
- Testing
- Python
- Agent orchestration
About
I'm a software engineer from Mexico, now living in Dublin with my wife and daughter. I came to code by way of project management and a love of design, and I have been building software for more than 13 years. I also can't stop teaching.