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Available for remote work

Portrait of Ariel Eitner, full stack developer based in Buenos Aires, Argentina

Ariel Eitner

Software engineering, artificial intelligence, and technology applied to institutions.

I build digital products, design software architectures, and explore how AI can solve concrete problems.

I share research, projects, and learnings on engineering, automation, and cybersecurity.

  • Software engineering
  • Applied AI
  • Cybersecurity
  • Institutional modernization
years of experience
6+years of experience
pages in production
125+pages in production
components in the portal I lead
300+components in the portal I lead
API routes written and maintained
145+API routes written and maintained

01About

Professional profile

I'm Ariel Eitner, a full stack developer with more than 6 years building scalable web applications in the TypeScript ecosystem —Next.js, React, NestJS, Prisma— and in PHP/Laravel, with Python for automation, scraping and data analysis.

I currently lead development of a multi-country edtech platform: dockerized microservices, international payment gateways, language-model integration, technical SEO, E2E testing and CI/CD on GitHub Actions.

My original training in electronics shaped how I approach software: explicit boundaries between components, traceable state, and a hard look at the cost of maintenance a few years out.

I work remotely with teams across Argentina, LATAM and the United States, both in full-time positions and on project contracts.

Languages

  • SpanishNative

    Mother tongue

  • EnglishB2 · Advanced

    Technical reading, writing and conversation

Education

  • Web Development with HTML, CSS3, JavaScript, PHP and MySQL

    Udemy

  • React Native for Android and iOS

    Udemy

  • Ongoing self-directed study

    Next.js, NestJS, TypeScript and software architecture

Based in

Buenos Aires, Argentina

Available for remote work

02Approach

How I work

Six areas where I concentrate the technical decisions that keep a product running in production.

  • 01

    Architecture and typed contracts

    Clear separation of concerns across layers and services, with shared TypeScript contracts verified at compile time. Microservices communicating over gRPC on protobuf schemas, with versioned contract libraries shared between backend and frontend.

  • 02

    Payment gateway integration

    Stripe, Mercado Pago, PayPal and Rebill on a multi-country checkout. Idempotent webhook processing, order-state reconciliation, retry policies and full transaction traceability in an in-house gateway.

  • 03

    Technical SEO

    Dynamic sitemaps, JSON-LD structured data (schema.org), URL migrations with 301 redirects, Core Web Vitals optimisation and automated Lighthouse audits driven by Puppeteer, tracked in Google Search Console.

  • 04

    Language-model integration

    Anthropic Claude and OpenAI APIs applied to product features: data extraction and analysis over legal documents, streaming writing assistance and conversational agents with persisted context.

  • 05

    Automated testing

    Playwright for E2E checkout and form flows, Vitest and Jest over domain logic, Cypress and PHPUnit depending on the stack. Static analysis and technical-debt control with SonarQube.

  • 06

    CI/CD and infrastructure

    GitHub Actions with separate development and production environments, Docker containers for production parity, orchestration with Docker Compose and Kubernetes, scheduled jobs on Vercel Crons and versioned SQL migrations.

03Stack

Technical stack

Technologies grouped by layer, applied in projects deployed to production.

Frontend

  • Next.js (App Router)
  • React 19
  • TypeScript
  • JavaScript (ES6+)
  • Tailwind CSS
  • shadcn/ui
  • Redux Toolkit
  • Zustand
  • TanStack Query
  • SWR
  • Framer Motion
  • Astro
  • React Native
  • React Server Components
  • Responsive mobile-first

Backend

  • NestJS
  • Node.js
  • Laravel (7–11)
  • PHP
  • Express
  • APIs REST
  • GraphQL
  • gRPC + protobuf
  • WebSockets
  • Webhooks
  • Prisma ORM
  • Eloquent ORM
  • JWT / OAuth 2.0

Databases

  • PostgreSQL
  • MySQL
  • MongoDB
  • Supabase
  • Redis
  • SQLite
  • Firebase
  • Prisma migrate
  • Full-text search
  • Índices y planes de consulta

Cloud & DevOps

  • Vercel
  • Render
  • Microsoft Azure
  • AWS S3
  • Docker
  • Docker Compose
  • Kubernetes
  • GitHub Actions
  • Cloudflare (WAF, CDN)
  • Nginx
  • Git

Payments & integrations

  • Stripe
  • Mercado Pago
  • PayPal
  • Rebill
  • Auth0
  • Zoho CRM
  • Google Sheets API
  • OpenAI API
  • Anthropic Claude API
  • Apollo.io
  • Vimeo API
  • WordPress

SEO & analytics

  • SEO técnico
  • Google Search Console
  • Sitemaps dinámicos
  • JSON-LD (schema.org)
  • Core Web Vitals
  • Lighthouse CI
  • Redirecciones 301
  • Google Analytics 4
  • Hotjar
  • Sentry

Quality & testing

  • Playwright (E2E)
  • Jest
  • Vitest
  • Cypress
  • Testing Library
  • PHPUnit
  • SonarQube
  • ESLint
  • Prettier
  • Husky
  • Storybook
  • Code review

Python & automation

  • Python
  • BeautifulSoup
  • Playwright
  • Puppeteer
  • pandas
  • pytest
  • Procesamiento de PDFs
  • Exportación a Excel

04Experience

Professional background

I combine technical leadership, institutional modernisation, and digital platform development, with a focus on infrastructure and security.

  1. BESEL

    Current

    CTO2026 — PresentTechnical leadership

    • I lead technical direction and the evolution of BESEL and its product ecosystem, setting priorities for architecture, quality, and modernisation.
    • I conducted a technical assessment of BESEL and Delegup covering architecture, dependencies, deployments, and security risks, and prepared an incremental roadmap to improve maintainability and reduce risk.
    • I analysed besel-website performance in a local Docker environment and identified opportunities to improve caching, resource usage, and operations.
    • I prepared an end-to-end cybersecurity assessment of the website, reviewing code, APIs, access controls, and dependencies, complemented by local testing and hardening priorities.
    • CTO
    • Arquitectura
    • Ciberseguridad
    • Docker
    • Railway
    • GitHub Actions

  2. Observatorio Catamarca

    Current

    Platform development and institutional modernisation2026 — PresentCatamarca

    • I am building Observatorio Catamarca, a document platform for organising and searching municipal ordinances, decrees, and resolutions.
    • I designed an architecture with Next.js, NestJS, Prisma, and PostgreSQL, with reproducible environments using Docker Compose.
    • I implemented security controls for a public-sector organisation: access and rotating refresh tokens, role-based permissions, attempt limits, strict validation, and operation auditing.
    • I hardened the runtime environment with a database on an internal network, unprivileged containers, and secrets kept out of images; I documented an initial private VPS deployment.
    • Next.js
    • NestJS
    • PostgreSQL
    • Prisma
    • Docker
    • JWT
    • RBAC

  3. MSK LATAM

    Lead Full Stack Developer2024 — August 2026Remote

    • I led development of a multi-country medical knowledge portal (edtech/ecommerce) with Next.js, React, TypeScript, and Tailwind CSS: ~50 pages, over 100 API routes, and 300+ components, internationalised with next-intl across LATAM.
    • I integrated Stripe, Mercado Pago, PayPal, and Rebill into checkout and a custom payment gateway, enabling online payments across multiple countries.
    • I built and maintained a Docker-based Laravel backend microservice architecture: payment gateway, Zoho CRM integration, PDF certificate generation with QR codes, and an administrative intranet.
    • I implemented end-to-end technical SEO: dynamic sitemaps, JSON-LD structured data, URL migrations, Core Web Vitals, and Lighthouse audits tracked in Google Search Console.
    • I automated tests with Playwright (E2E for checkout and forms), Vitest, and Jest, and code-quality checks with SonarQube.
    • I set up CI/CD with GitHub Actions (dev/prod environments), Docker, and Vercel cron jobs; data on Supabase (PostgreSQL) with versioned migrations.
    • I integrated Auth0 and reCAPTCHA v3, Cloudflare (WAF, CDN) for perimeter security, and monitoring with Sentry, Google Analytics, and Hotjar.
    • I built an in-person sales assistant for the commercial team (Next.js, shadcn/ui, Zustand) that creates leads, contacts, and orders in Zoho CRM, syncing to Google Sheets every 5 minutes via Vercel Crons.
    • Next.js
    • TypeScript
    • Laravel
    • Docker
    • Supabase
    • Stripe
    • Playwright

  4. ScriptAI

    Full Stack Software Engineer2023 — 2024Remote

    • Designed and built an AI SaaS platform end to end: frontend, backend and database.
    • Integrated the OpenAI API for a conversational chatbot and a text editor with real-time AI assistance.
    • Implemented secure authentication with Auth0 (SSO, sessions and roles) and cloud infrastructure on Microsoft Azure.
    • React
    • Node.js
    • OpenAI API
    • Auth0
    • Azure

  5. Freelance

    Freelance Developer2019 — 2022Buenos Aires

    • Built a mobile application with React Native (Android/iOS) using Firebase, GraphQL (Apollo Server) and MongoDB.
    • Delivered complete websites for real-estate and service clients with PHP, MySQL, JavaScript and SASS, managing the client relationship directly.
    • React Native
    • GraphQL
    • MongoDB
    • PHP
    • MySQL

05Projects

Selected projects

Personal platforms and client products, with the stack and scale of each.

75 pages · 45 API routes in production

Argentine Law Observatory

Freemium platform that digitises, searches and explains Argentine legislation.

Laws, emergency decrees, codes and case law in one place. NestJS + Prisma backend with 24 models on Supabase/PostgreSQL and a Next.js frontend. Contract analysis with Anthropic Claude, Mercado Pago payments via webhooks, graph visualisation with D3, full-text search and industrial-grade SEO: dynamic sitemaps, JSON-LD and a custom audit built on Lighthouse + Puppeteer.

  • NestJS
  • Prisma
  • Supabase
  • Next.js
  • Claude API
  • Mercado Pago
  • D3

Backtesting without look-ahead bias

Quantitative trading platform

Custom candle-by-candle backtesting engine, free of look-ahead bias.

Multi-core optimisation, walk-forward analysis and Monte Carlo simulations, with Sharpe, Sortino and Calmar metrics. Includes a paper-trading bot fed with Binance data and a web dashboard to follow the strategy.

  • Python
  • pandas
  • Binance API
  • Dashboard web

Domus Commerce

Headless website builder engine with a visual editor.

NestJS microservices on Supabase, a shared TypeScript contract library across services, a Next.js renderer and a drag-and-drop visual editor built with @dnd-kit.

  • NestJS
  • Supabase
  • Next.js
  • @dnd-kit
  • TypeScript

B2B lead automation tool

LinkedIn scraping with email enrichment.

Profile extraction enriched through the Apollo.io API and exported to Excel. Distributed as a desktop application (.exe), with pytest coverage and versioning.

  • Python
  • Playwright
  • Apollo.io
  • pytest

Nuum · Chanchito

Fintech apps for personal finance management.

NestJS backend with MongoDB and Prisma, JWT authentication over HTTP-only cookies and dashboards with Recharts. E2E with Cypress, quality with SonarQube, a code-standards manifesto and deployment with Docker/Kubernetes.

  • NestJS
  • MongoDB
  • Prisma
  • Recharts
  • Cypress
  • Kubernetes

MedPrime

Medical platform deployed across three environments.

MVP with a Laravel 11 backend (Octane, Sanctum, social OAuth) and a Next.js frontend. Video through the Vimeo API, storage on AWS S3 and payments with Mercado Pago, deployed across dev/tst/prod on Docker.

  • Laravel 11
  • Next.js
  • Vimeo API
  • AWS S3
  • Docker

gRPC microservices monorepo

API gateway and services communicating over protobuf.

A gateway plus NestJS services communicating over gRPC with protobuf contracts, persistence with Prisma + MySQL and local orchestration with Docker Compose.

  • NestJS
  • gRPC
  • protobuf
  • Prisma
  • MySQL

ScriptAI

AI-assisted screenplay editor.

SaaS platform with a text editor that suggests and rewrites in real time using the OpenAI API, plus a conversational chatbot. Auth0 authentication and infrastructure on Microsoft Azure.

  • React
  • Node.js
  • OpenAI API
  • Auth0
  • Azure

✦ FARO

Municipal legislation, made clear.

A platform to organize, explore and connect a city’s legislation. Discover the proposal for municipal governments.

Explore FARO (Spanish)

06Tech map

The 15 areas of web development, and where I stand in each

A serious web application isn't «frontend and backend». It's the intersection of fifteen disciplines that overlap constantly. I built an interactive map of all of them and the technologies I use in each.

  • Architecture, performance, cybersecurity and technical SEO
  • Databases, infrastructure, observability and testing
  • Reliability, accessibility, compatibility and code quality

15 areas · 115 technologies

Explore the tech map

07FAQ

Frequently asked questions

What people usually ask before we start working together.

  • What technologies does Ariel Eitner use?

    I work mainly with Next.js, React and TypeScript on the frontend, and NestJS, Node.js and Laravel on the backend. Databases in PostgreSQL, MySQL and MongoDB with Prisma ORM, infrastructure on Docker, Kubernetes, Vercel and Cloudflare, and Python for automation, scraping and data analysis.

  • Do you work remotely?

    Yes. I work fully remote from Buenos Aires, Argentina, with teams in Argentina, LATAM and the United States, on hours that overlap with American time zones. I'm open to both full-time positions and project contracts.

  • What kind of projects do you take on?

    Web platforms with a real backend: multi-country ecommerce and checkout, content portals with demanding SEO, SaaS products with language-model integration, APIs and microservice architectures. Also migrations and audits of performance, security and technical SEO on systems already in production.

  • How much experience do you have?

    More than 6 years of professional development. I currently lead a multi-country edtech platform with over 125 pages and 145 API routes in production, after three years freelancing and a stint at an AI startup.

  • Do you integrate payment gateways?

    Yes: Stripe, Mercado Pago, PayPal and Rebill, including an in-house gateway with idempotent webhook processing, order-state reconciliation and full transaction traceability across several countries.

  • How do we start?

    Email me or reach out on LinkedIn with a description of the project. I come back with a proposal covering scope, suggested architecture and an estimate within a few days.

08Contact

Available for remote projects

I work remotely from Buenos Aires, Argentina. Open to full-time positions and project contracts.

ariel.10.e@hotmail.comDescargar CV (ES)Download CV (EN)