maarkn.dev
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Marco Filho · maarkn

I build digitalproducts thatpeople actually use.

Senior fullstack engineer · 5+ years · Remote from Brazil

I help companies turn ideas into clean, fast and reliable products — from the first sketch to the version that ships and grows. Equally comfortable shaping the architecture, writing the code, and talking to the people who use it.

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A few numbers

Six years of building things that don't break.

0

Years writing software professionally

0+

Products and platforms delivered

0

Languages and frameworks in daily use

0

Countries with clients I've worked with

AboutWork history

A builder who sweats the details and ships the work.PROFESSIONAL_EXPERIENCE

I'm Marco — most people online know me as maarkn. I'm a senior fullstack engineer based in Goiânia, Brazil, working with clients and teams around the world.

I started writing software professionally in 2019 and never really stopped. Over the years I moved from frontend trainee to leading the architecture of products used by thousands — VoIP platforms, fintech apps, real-estate assistants, museum sites, agronomy chatbots, and a few things I can't talk about yet.

What I really enjoy is being involved end-to-end: understanding what people actually need, designing how the system should behave, writing the code that makes it real, and staying close while it goes live and grows. I care about clean architecture, but I care more about software that works, doesn't surprise the team that maintains it, and gives the user a smooth ride.

When I'm not coding, I'm usually studying — currently improving my English to relocate abroad, and exploring how AI agents can be useful day-to-day instead of just impressive in demos.

How I work

  • End-to-end ownership

    From the first conversation to the version running in production. I don't hand things off and disappear.

  • Clear, plain communication

    I translate between business and code. Stakeholders get straight answers, not jargon.

  • Pragmatic over perfect

    I ship the simplest thing that solves the problem, then iterate when reality pushes back.

  • Respect for the next person

    Code is read more than it's written. I leave the codebase a little better than I found it.

Career timeline

  1. Now · Dec 2024 — Now

    Fullstack Developer & Consultant — Self-Employed · Freelance

    Building end-to-end products as a freelancer: a refactored Flutter app with in-app purchases, several WhatsApp assistants powered by LLMs, a carbon-credit reporting platform, a real-estate chatbot for Miami, and a few security and performance audits.

    Read full case

  2. Jan 2024 — Nov 2024

    Senior Developer L2 — Nectar CRM

    Led the architecture of a VoIP product integrated with the company CRM. Designed billing rules, real-time provisioning, call recording and transcription, multitenancy and team management.

    Read full case

  3. Aug 2022 — Jan 2024

    Fullstack Engineer (Remote) — Sevencred

    Built a fintech API for FCO loans with a microservices mindset, a Flutter app for applications, a Ghost-based portal, and crawlers ingesting data from public Brazilian gov APIs.

    Read full case

  4. Oct 2021 — Aug 2022

    Senior Fullstack Developer (Remote) — Ecto Digital

    Migrated Google reviews ingestion from batch to real-time events. Led two junior developers, set the code-review process, and shipped a subscription system to onboard small clients.

    Read full case

  5. Jun 2021 — Oct 2021

    Frontend Developer (Hybrid) — VendorHub

    Drove UI standardization, refactored the core product registration flow, and built a Chrome extension to analyze Mercado Livre ad performance directly inside the marketplace.

    Read full case

  6. Feb 2021 — Jun 2021

    Fullstack Web Developer (Remote) — Ecto Digital

    Shipped features on a Google My Business listings platform, managed deployments, and improved a few Gatsby blogs along the way.

    Read full case

  7. Feb 2020 — Jan 2021

    Frontend Developer JR (Remote) — Collectgram

    Built referral and subscription flows, fixed bugs and grew the admin dashboard of a collection-management product.

    Read full case

  8. Jul 2019 — Jan 2020

    Frontend Trainee (Hybrid) — Collectgram

    Where it all started: a Vue.js marketplace dashboard and email marketing templates with Pug and Sass.

    Read full case

Selected workSelected work

Things I've shipped that people actually use.PROJECT_REGISTRY

A small slice of the products and platforms I've built over the last few years — for clients, employers and a couple of side bets. Some I can show in detail, others stay anonymous behind an NDA.

See all projects
miami-real-estate-assistantLive

Miami Real Estate Assistant

2025

AI · Chatbots

A WhatsApp assistant for a Miami real-estate agency that captures leads, syncs properties from MLS and answers questions like a tireless junior agent.

  • TypeScript
  • NestJS
  • LLM · MCP
  • MLS
municipalities-chatbotLive

Municipalities Chatbot

2024

AI · Chatbots

City-by-city WhatsApp helper that crawls each town's website, indexes it, and answers citizens' questions about services, opening hours and documents.

  • TypeScript
  • Vector store
  • Web crawling
  • WhatsApp
voip-platformInternal

VoIP Platform

2024

Backend · APIs

Calls, recordings, transcriptions and dynamic billing in a single VoIP product wired into the company's CRM.

  • NestJS
  • Asterisk
  • WebSockets
  • MongoDB
fintech-loan-apiUnder NDA

Fintech Loan API

2023

Backend · APIs

A loan platform for a Brazilian agribusiness fund: APIs, a Flutter app for applicants, and crawlers ingesting public government data.

  • NestJS
  • Microservices
  • Flutter
  • MongoDB
carbon-credit-platformLive

Carbon Credit Platform

2025

AI · Chatbots

Triage chatbot plus an automated report engine that turns raw project data into legal-style viability documents.

  • TypeScript
  • LLM
  • PDF generation
  • NestJS
drug-leaflet-platformLive

Drug Leaflet Platform

2025

Web app

A high-performance, SEO-first reference for medication leaflets — Astro on the front, NestJS and ANVISA crawling on the back.

  • Astro
  • NestJS
  • Web crawling
  • SEO

ToolkitTechnical stack

The tools I reach for, day after day.SYSTEM_ARCHITECTURE

These are the languages, frameworks and ideas I use most. The list isn't exhaustive — I learn whatever the project needs — but it's an honest snapshot of where I'm fluent.

01

Frontend

Interfaces people actually want to use.

  • TypeScript6y
  • React5y
  • Next.js4y
  • Vue.js3y
  • Nuxt3y
  • Astro1y
  • Tailwind CSS4y
  • HTML / CSS6y
02

Backend & APIs

The plumbing that has to work every time.

  • Node.js6y
  • NestJS4y
  • Express5y
  • REST APIs6y
  • Microservices4y
  • Kafka2y
  • RabbitMQ3y
  • WebSockets3y
03

Mobile

Apps that ship to real stores.

  • Flutter3y
  • React Native2y
  • Dart3y
  • Firebase3y
  • In-App Purchases2y
  • App Store / Play Store2y
04

Data & Storage

Where things live and how they're found.

  • PostgreSQL6y
  • MongoDB5y
  • Redis5y
  • Elastic Search2y
  • BigQuery1y
  • ETL / Web crawling3y
  • Vector stores · LLM1y
05

Infra & DevOps

Putting code in front of users, safely.

  • Docker6y
  • AWS5y
  • GCP2y
  • Nginx4y
  • Linux6y
  • OAuth2 / Keycloak3y
  • CI/CD5y
06

Practices & Soft skills

How I work with code and with people.

  • DDD4y
  • SOLID
  • TDD
  • Design Patterns
  • Code review · Mentoring
  • Multitenancy
  • SEO-focused dev
  • Stakeholder communication

Capabilities

  • System Design92%
  • API Architecture95%
  • Frontend Engineering88%
  • DevOps & Infra82%
  • Mobile Delivery80%
  • Data Modeling86%

Get in touch

Have something you'd like to build? Let's talk.> INITIATE_CONTACT

Quickest path is the form below — I read every message and reply within a couple of working days. If you prefer a different channel, pick whatever fits.

Available for new projects

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Latest writingGhost CMS integration

Latest LogsLatest Logs

Field notes I've published recently. Open one or jump to the full archive.

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Featured post
AI

From FAQ trees to RAG: what changed in my chatbots

I used to build chatbots as decision trees. Then a vector store and a few well-named files made everything I'd written feel like 1998. A field note on what works.

·5 min read