Skip to content
jr/dev
ES

Open to new projects

Javier Rodríguez

Full Stack & Backend Developer

Buenos Aires, Argentina · Available remote

I build complete digital products: architecture, backend, frontend and infrastructure. From the first line of code to the server in production.

See projects Download CV Contact ↗

01 · About

Product engineer, not just a developer.

I build complete digital products: architecture, backend, frontend and infrastructure. From the first line of code to the production server.

I have hands-on experience solving complex technical problems in real-world contexts: high-traffic systems, multi-gateway payment integrations, self-managed VPS infrastructure, real-time IoT platforms and LLM integration in products.

I started in electronics and moved to software. That gives me a perspective most developers don’t have — I understand the hardware behind the system.

/01 years of experience
5+
/02 users impacted
50K+
/03 BRL revenue on projects I led
1M+
/04 courses passed in Systems Engineering
25
Foto de Javier Rodríguez
Javier Rodríguez · Buenos Aires, Argentina

02 · Projects

Selected work

Five products with real traction and two earlier pieces. Sorted by impact, not by date.

B2C SaaS · SMM · High-traffic e-commerce 01 / 2023 — 2025

EngajaMaisVoce

Premium social-growth platform for the Brazilian market.

Role
Tech Lead · Full Stack & Infra Engineer
Period
Dec 2023 — Oct 2025
Metrics
  • 50K+ active users
  • 1M+ BRL revenue
  • 6 payment gateways
  • 3 repos built from scratch

Sole technical owner for two years of a B2C SMM platform that generated 1M+ BRL and moved 50K+ users. Three-repo architecture, six payment gateways integrated, self-managed VPS infrastructure with anti-DDoS and geo-blocking, and a resilient microservice that abstracts the instability of external SMM providers.

  • React 19
  • TypeScript
  • Vite
  • Node.js
  • Express
  • MySQL
  • MongoDB
  • Firebase
  • +5
See full case study →
EngajaMaisVoce landing page with the "buy real followers" proposition.
Subscription platform · Real-time audio 02 / 2024 — 2025

Elemental Is Life

Subscription platform with a real-time multichannel audio mixer.

Role
Full Stack Developer (Freelance)
Period
Dec 2024 — Jun 2025
Metrics
  • 5 simultaneous real-time tracks
  • PayPal recurring subscriptions
  • S3 storage with automatic metadata

Wellness and sound-healing platform with a player that mixes up to five simultaneous audio tracks in real time, without lag or main-thread blocking. NestJS backend with an ultra-relational schema, S3 storage with automatic metadata and PayPal subscriptions synced via webhooks.

  • React
  • TypeScript
  • Vite
  • NestJS
  • PostgreSQL
  • Prisma
  • AWS S3
  • WebAudio API
  • +3
See full case study →
Elemental Is Life home page with a mystic and scientific aesthetic.
IoT · Real-time industrial monitoring 03 / 2023 — Present

Eleconar IoT

Real-time industrial IoT platform with MQTT and custom microcontrollers.

Role
Embedded & Full Stack Developer
Period
Feb 2023 — Present

Web platform for industrial monitoring connected to plant devices over MQTT. NestJS backend with Redis distributed cache and Next.js frontend consuming live streams. C/C++ firmware for microcontrollers and Modbus communication with PLCs. The project where my electronics background and modern software meet.

  • Next.js
  • NestJS
  • TypeScript
  • PostgreSQL
  • Redis
  • MQTT
  • WebSockets
  • C
  • +2
See full case study →
Screenshots coming soon
LMS · Membership platform 04 / 2023

WhoIsOutlier

Membership LMS with Stripe in production and AWS S3 presigned URLs.

Role
Full Stack Developer (Freelance)
Period
2023
Metrics
  • 9 relational models
  • Stripe HMAC-verified webhooks
  • S3 presigned URLs with expiry

LMS platform built for a YouTuber with audience, managing Stripe subscriptions, serving protected content with S3 presigned URLs and organizing material in a Super Category → Category → Subcategory hierarchy with per-user progress tracking. Stack AdonisJS 6 + PostgreSQL + React 19.

  • AdonisJS 6
  • TypeScript
  • PostgreSQL
  • Lucid ORM
  • Stripe
  • AWS S3
  • React 19
  • Vite
  • +4
See full case study →
Premium landing with iPhone mockup and membership copy.
AI platform · LLM chat 05 / 2023

MentorProfit

4 AI mentors configurable from MongoDB, on top of GPT-4o-mini.

Role
Full Stack Developer (Freelance)
Period
2023
Metrics
  • 4 AI mentors with their own personality
  • GPT-4o-mini inference engine
  • MongoDB prompts editable live

Full-stack chat platform with four AI mentors specialized in personal finance. Each character has its system prompt in MongoDB and can be edited live without touching code. Node + Express + MongoDB backend with rate limiting, Google AdSense monetization and AdBlock detection.

  • React 18
  • TypeScript
  • Vite
  • Node.js
  • Express
  • MongoDB
  • OpenAI SDK
  • Framer Motion
  • +2
See full case study →
MentorProfit hero with isometric illustration of a financial city.

More projects

Berta Producciones hero with typography and night imagery.

2022 · Landing · Web catalog

Berta Producciones

Landing + catalog for an event-equipment rental business.

See full case study →
Main screen with the grid of TikTok Coins packages.

2023 · Frontend · UI clone

TikTok FreeCoin

Faithful UI clone of the TikTok Coins recharge screen.

See full case study →

03 · Stack

Tools I work with daily

Languages

  • TypeScript
  • JavaScript
  • Python
  • C
  • C++

Frontend

  • React
  • Next.js
  • Vue 3
  • Astro
  • Vite
  • TailwindCSS

Backend

  • Node.js
  • NestJS
  • Express
  • AdonisJS
  • FastAPI

Databases

  • PostgreSQL
  • MySQL
  • MongoDB
  • Redis
  • Prisma

Infrastructure

  • VPS / Nginx
  • Docker
  • PM2
  • Cloudflare
  • Keycloak

Observability

  • Grafana
  • Prometheus
  • Loki
  • Jaeger
  • OpenTelemetry

Cloud

  • AWS S3
  • Firebase
  • Cloudflare Pages

IoT / Real-time

  • MQTT
  • WebSockets
  • WebAudio API
  • Modbus

Payments

  • Stripe
  • Mercado Pago
  • OpenPix
  • PagHiper
  • PayPal

AI / LLMs

  • OpenAI API
  • DeepSeek
  • Agent integration

04 · Experience

Career

  1. Apr 2025 — Present

    NetJamGroup

    employed

    Frontend Developer

    Building interfaces and features on production-grade products.

  2. Dec 2023 — Oct 2025

    EngajaMaisVoce

    employed

    Tech Lead · Full Stack & Infra

    Sole technical owner for two years. 3-repo architecture, multi-gateway payment integrations, VPS infrastructure under constant attack.

  3. Feb 2023 — Present

    Eleconar

    employed

    Embedded & Full Stack Developer

    Industrial real-time IoT platform, MQTT communication and microcontroller programming in C/C++.

  4. Oct 2023 — Feb 2024

    DaaL

    employed

    Full Stack Developer

    Feature development on a Node + React stack for B2B projects.

  5. 2022

    IMSA Conductores Eléctricos

    employed

    Technical internship

    First formal experience, transition from the electronics world.

  6. Dec 2024 — Jun 2025

    Elemental Is Life

    freelance

    Full Stack Developer

    Subscription platform with a real-time multichannel audio player.

  7. 2023

    WhoIsOutlier

    freelance

    Full Stack Developer

    Membership LMS with Stripe and AWS S3 for a YouTuber with audience.

  8. 2023

    MentorProfit

    freelance

    Full Stack Developer

    Chat platform with 4 AI mentors configurable from MongoDB.

05 · Education

Education

  • In progress

    Systems Engineering

    Universidad Abierta Interamericana (UAI)

    25 courses passed

  • Completed 2022

    Electronics Technician

    EEST N°1

  • 2021 — 2022

    Competitive Programming Preparation

    UNLAM

  • 2021

    Node.js Development · Full Stack Developer

    UTN

06 · Contact

Let’s work together.

Available for full-time roles and freelance projects that require technical judgement and the ability to take a product from zero to production.

Email javi.r49915@gmail.com LinkedIn linkedin.com/in/jotaerrec GitHub github.com/jotaerrec
Download CV (PDF) Email