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Code By
Eugenio
Guevara
BuildingproductionapplicationsforUS-basedagenciesandfintechstartups,fromAIpipelinesandreal-timesystemstocross-platformmobileapps.
AWS Certified Solutions Architect with an economics background, combining cloud-native expertise with full-stack development.
Led the development of YEYAR, a real estate investment platform for presale properties in Mexico, now structured as a monorepo where the investor web platform, the admin platform for the internal team and developers, and the mobile app share one codebase. Developed interactive property maps with the Google Maps API, investor dashboards, real-time chat, and in-app unit reservations via Stripe. Implemented SEO and metadata optimization, increasing organic traffic by 30%, and created a CMS for real estate insights, boosting user engagement.
Next.js, TypeScript, Hono, Drizzle ORM, PostgreSQL, Stripe, Turborepo
Developed a cross-platform YEYAR mobile app using React Native and Expo, enabling real-time property alerts via Expo push notifications. Built a Pusher-based chat for real-time messaging and offline data sync for seamless UX. Integrated haptic feedback and location based features, published on the App Store and Google Play.
React Native, Expo, Stripe, Pusher, Native APIs
Built MiContax, a tax-preparation SaaS for Mexico that connects to the Contalink accounting API to guide users through their filings. Developed the authenticated dashboard, subscription billing with Stripe, and a rich-text blog editor on top of a typed API. Also built the marketing site for CMS Consultores, the accounting firm behind the product, with lead-capture forms, a resource hub, and a full SEO setup.
Next.js, Hono, Clerk, Drizzle ORM, PostgreSQL, Stripe
InsertBid is an online auction marketplace for gaming collectibles, where verified sellers list vintage video games, trading cards and memorabilia for collectors to bid on. I joined an existing React and Express codebase rather than building it from scratch: contributed improvements to the platform and its bidding system, and focused on SEO, search ranking and performance optimisation measured against Core Web Vitals.
React, Express, Bootstrap, SEO, Core Web Vitals
Led a 3-developer team at a New York-based fintech company to architect an advanced AI system achieving 90% accuracy on FinanceBench evaluations. Built a sophisticated RAG (Retrieval-Augmented Generation) pipeline integrating Claude with SEC EDGAR database for real-time financial document analysis. The system processes 10-K, 10-Q, and 8-K filings, extracting key financial metrics and generating intelligent responses to complex investment queries. Implemented vector embeddings with pgvector for semantic search across millions of financial documents, while integrating multiple financial APIs for live market data, earnings calendars, and EPS projections.
Next.js, Vercel AI SDK, OpenAI, Anthropic, pgvector, Supabase
Also built
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Real-time ticket-drop alerts for a New York client: a Flutter app over a Node.js and Puppeteer scraper fleet on Google Cloud, with stealth plugins, residential proxies and CAPTCHA solving at 98% extraction success.
A browser extension that selects adjacent seats in one click on every major ticketing platform, using DOM pattern recognition, a custom overlay UI framework and encrypted licensing, cutting bulk purchase time by 80%.
A Rust engine that runs several strategies against one live Polymarket order book over WebSockets, with record-and-replay backtests on the same code, deployed as concurrent AWS instances beside a Go copy-trading bot.
An ERC-20 token and companion dApp built as a learning project: mint, buy and sell through a minimal MetaMask and Web3.js UI, deployed to Ethereum testnets with attention to gas costs and contract security.
How I build
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Stack by area
Highlighted = core stack
TypeScript end to end; Go when a service must stay small and fast; Java on JVM services; Rust and Python for engines and data work.
Next.js App Router with Server Components, Tailwind and shadcn/ui — the same React I ship on native; Astro for content-heavy sites, Angular where a client already runs it.
React Native with Expo and EAS, shipped to both stores for YEYAR; Ionic on Angular codebases.
Hono on the edge with Drizzle for typed SQL; NestJS and Express for larger teams and legacy APIs; Spring Boot on the JVM side.
PostgreSQL first (Neon, Supabase) with pgvector for embeddings; MySQL and MongoDB where a project has them.
AWS architecture (certified) — Lambda, ECS, S3, SQS and SNS — with Terraform for infrastructure as code; Pub/Sub on Google Cloud, Vercel for Next.js, Docker and GitHub Actions for CI.
Claude and OpenAI through the Vercel AI SDK; RAG pipelines over pgvector for financial document analysis.
Stripe (incl. Connect) for payments, Clerk for auth, Resend for email, Cloudinary and Vercel Blob for media, Puppeteer for headless jobs.
Claude Code and MCP servers in the daily loop, Bun for scripts and installs, Vitest and Playwright for tests, Turborepo for monorepos, Zod at every boundary, Figma for handoff.
Open source & activity
1,143 contributions in the last 12 months across 176 active days; busiest day Sep 21, 2026 with 214 contributions.
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