Available for new projectsTech Lead · Full Stack · Architecture

I build entire platforms, not just screens.

I work from the architecture sketch to the app in the store: NestJS and Java services, React Native apps, Next.js consoles, and the infrastructure that keeps all of it standing.

Get in touch See case studies

Florianópolis, Brazil · Remote

TypeScript
NestJS
Next.js
React
React Native
Node.js
gRPC
RabbitMQ
PostgreSQL
Docker
AWS
Java / Spring

Marcelo Mafra

Fullstack Developer | Microservices Expert

The scale of what I have shipped

Numbers from real production systems — not from study projects.

21+

services in production

Node/NestJS and Java/Spring microservices, with separate gateways per audience.

mobile apps shipped

Android and iOS, including a white-label multi-tenant line with OTA updates.

Turborepo monorepos

With a design system, shared contracts, and quality pipelines.

industries served

Payments fintech, edtech, and B2B SaaS.

Engineering case studies

Systems I designed and built. Clients are not identified; the architecture and decisions are real.

Payments fintech

A payments platform with 21 services

A payments system split into Node and Java services, wired straight into partner banks, with web and mobile products running on top of those same services.

Domain split into independent services (IAM, wallet, orders, payments, receivables, tax, notifications) with distinct gateways for the admin console and the end customer.
Dedicated Java/Spring services for Pix, bank slips, receivables, and invoice issuing, isolating each banking integration from the product core.
A Next.js console and a React Native app on the same services, with CI/CD on Docker, PM2, and GitHub Actions.

Stack

NestJS
Java / Spring Boot
gRPC
RabbitMQ
PostgreSQL
Redis
React Native
Next.js

Edtech

White-label apps for schools

A single codebase produces independent apps per institution — branding, bundle, integrations, and features all defined by tenant configuration.

A tenant registry driving both build time (bundle ID, icon, splash) and runtime (theme, LMS URL, feature flags) from one source.
Continuous Android and iOS releases with Expo/EAS plus OTA updates triggered by pushes to the main branch.
NestJS backends covering auth, cloud files, push, and email, alongside Next.js admin consoles and the Ionic/Angular mobile LMS.

Stack

React Native
Expo / EAS
NestJS
MySQL
Next.js
Ionic / Angular
GitHub Actions

Scientific SaaS

Botanical identification SaaS driven by spectroscopy

A platform wiring a near-infrared scanner to statistical identification models, with the same interface running in the browser and on the desktop.

A Next.js PWA as the single source of UI, also packaged inside a Tauri/Rust desktop shell that bridges the hardware.
NestJS microservices behind a single gateway, with per-institution data isolation through PostgreSQL row level security.
A monorepo with its own design system, typed HTTP contracts, and Storybook as the living UI reference.

Stack

Next.js PWA
Tauri / Rust
NestJS
PostgreSQL RLS
Turborepo
Storybook

Real-estate SaaS

Real-estate SaaS platform

CRM, operations, property catalog, and client portal on a multi-tenant microservice architecture.

NestJS services communicating over gRPC behind an API Gateway, with contracts versioned in a shared package.
Domain modeling for properties, deals, and brokers, with per-tenant authorization and data isolation.
A pnpm + Turborepo monorepo whose domain, UI, and config packages are reused across backend and frontend.

Stack

NestJS
gRPC
API Gateway
PostgreSQL
Redis
Next.js
Turborepo

SaaS for dance schools

Ritmar — multi-tenant management for academies

My own product, from zero to production: enrollments, classes, graduations, recurring billing and POS, with a public website per school.

Recurring billing via Pix and card with one gateway per school, idempotent webhooks, reconciliation and an audit trail.
Per-tenant isolation in PostgreSQL and a public website per subdomain or custom domain, with indexing controlled by tenant status (robots, noindex and sitemap).
Full operation: implantation sales flow, per-school provisioning and Docker delivery with encrypted backups and scheduled billing routines.

Stack

NestJS
Next.js
PostgreSQL
Mercado Pago / Asaas
Turborepo
Docker

AI in the engineering workflow

I work AI-first. Not faster autocomplete — the engineering process redesigned around agents, held to the same rigor as any system in production.

Spec and plan before code

Any change of substance starts from a spec that pins down the problem, the constraints and the acceptance criteria, and from a plan broken into verifiable tasks, each with its own test. An ambiguous spec is a requirements bug: cheaper to fix there than thirty files later.

Spec-driven development

Each phase on the right model

Planning, implementing, debugging and reviewing are different jobs, and models are not equally good at all four. Each phase is routed to the one that performs best on it, and whoever writes the plan is not the one implementing it. Execution stays sequential and isolated: one task at a time, on its own branch.

Orchestration across models

Project standards, versioned

Module layout, logging and testing conventions live in the repository as executable instructions, reviewed in PRs like anything else. A new agent inherits the rule instead of guessing; when the rule changes, it changes for everyone in the same commit.

Context in the repo

Tooling over a protocol

The agent reads the task board, the database, the browser and CI over MCP, instead of relying on context pasted by hand. It trades “what I remember about the system” for “what the system just answered”.

MCP

Evidence before claims

A failing test before the implementation; lint, typecheck, coverage and end-to-end runs in CI as an objective gate. A test that depends on timing, or that checks implementation instead of behavior, gets rewritten — never labeled flaky and ignored.

TDD and CI

Human review at the merge

I read everything that comes back before opening the PR. Agents speed up producing code and, with it, producing wrong code — the gain is in the gates that catch it early, not in trusting more.

The merge gate

Applied to real products, not demos: this is how I moved a six-person squad to a spec-driven flow in edtech, and how I build a microservice SaaS platform for the real estate market today.

Projects

View gallery

Ritmar

My own product, in production: a management platform for gyms and dance schools — enrollments, classes, graduation events, recurring billing, a graduation-night POS and a public website per school, on a subdomain or custom domain.

My role

Founder and engineer. From the billing model to deployment: a NestJS API, three Next.js applications, multi-tenant PostgreSQL and the production operation.

NestJS

Next.js

PostgreSQL

TypeORM

Visit

Oniapp · Portal do aluno

Study app for schools that run on Moodle. Each institution gets its own app in the stores, with its own brand and colors, but all of them come from a single codebase. Students sign in with their school account and reach courses, files, and announcements from the phone.

My role

Tech Lead and full stack developer. I designed the system that turns one codebase into one app per school, wrote the app in React Native with Expo, and handle the App Store and Play Store releases through EAS.

React Native

Expo

Expo Router

NativeWind

Visit

Seja · App

Wellbeing app published on the App Store and Google Play. It keeps routines, habits, and content in one place, with social sign-in and reminders that bring people back.

My role

Tech Lead and full stack developer. I built the app in React Native with Expo — navigation, offline handling, and the releases to both stores through EAS.

React Native

Expo SDK 54

NativeWind

Zustand

Download

Comvanilla

Platform for real estate agencies: property listings, deal pipeline, agent routines, and the portal the end client browses. Each agency works with its own data, isolated from the others inside the same platform.

My role

Full stack developer. I split my time between the NestJS services that talk over gRPC, the data modeling, and the Next.js screens.

Next.js

NestJS

gRPC

PostgreSQL

Visit

Postpay · Plataforma

The services running behind a payments fintech: accounts and identity, wallet, orders, charges, settlements, and tax documents, wired straight into partner banks.

My role

Full stack developer working on the backend. I wrote services in NestJS and in Java with Spring Boot, handled how they talk to each other over gRPC and RabbitMQ, and ran them in Docker.

NestJS

Java

Spring Boot

gRPC

Visit

Mince Joias

Online jewelry store: catalog, cart, checkout, and a panel where the owner updates products and follows orders herself.

My role

Full stack developer, freelance. I delivered the store and the panel on my own, from the first layout to the AWS deploy.

Next.js

TypeScript

Tailwind CSS

AWS

Visit

Experience

Hire me

Onilearning

Tech Lead / Full Stack Engineer · Independent contractor

Jan 2026 – Present · Remote

Technical leadership across squads: architecture decisions, engineering standards, code review, and mentoring.
Technical direction of the edtech products: LMS, student portal, mobile apps, and backends.
Architecture and evolution of a white-label, multi-tenant student portal with React Native and Expo.
Mobile LMS delivery (Ionic, Angular, and Cordova) with Android and iOS releases.
REST APIs with NestJS and TypeScript using MySQL, JWT auth, cloud file storage, push notifications, and email.
CI/CD and continuous delivery with Docker, GitHub Actions, and Expo Application Services (EAS).
Quality practices in monorepos: automated tests, linting, pre-commit hooks, and coding standards.

Comvanilla

Full Stack Engineer · Independent contractor

Oct 2025 – Present · Remote

Full-stack delivery of a real-estate SaaS platform (CRM, operations, listings catalog, and client portal).
Microservice architecture with NestJS, gRPC inter-service communication, and an API Gateway.
Web interfaces with Next.js (App Router), React, and Tailwind CSS.
Domain and data modeling for CRM, properties, deals, and brokers.
Authentication, authorization, and data isolation in a multi-tenant environment.
PostgreSQL with TypeORM, Redis caching, and external service integrations.
Monorepo quality and DX (pnpm and Turborepo): automated tests, code review, and standardization.

Ritmar

Founder & Software Engineer · Own product

Apr 2026 – Present · Remote

Multi-tenant management SaaS for gyms and dance schools: enrollments, classes, graduations, recurring billing and POS.
Pix and card billing with one gateway per school, idempotent webhooks, reconciliation and an audit trail.
A public website per school, on a subdomain or custom domain, with indexing controlled by tenant status.
Monorepo with a NestJS API and three Next.js applications; Docker delivery with unit and end-to-end tests in CI.

Postpay

Full Stack Engineer · Independent contractor

Dec 2022 – Oct 2025 · Remote

Evolution of payments fintech products: admin console, mobile app, and microservice backends.
NestJS/Node.js microservices with gRPC, messaging, PostgreSQL, Redis, and TypeORM.
Java/Spring Boot financial services (Pix, bank slips, receivables, and NFSe) integrated with partner institutions.
Admin web experience with Next.js, React, TypeScript, and Tailwind CSS.
React Native + Expo mobile app for Android and iOS with REST APIs, auth, and push notifications.
Sensitive-data protection, cloud storage, and key management practices.
CI/CD and operations with Docker, PM2, GitHub Actions, and EAS; reviews and tests in monorepos.

Griebler Remodeling

Full Stack Engineer · Freelance

Jan 2024 – Feb 2024 · Remote (USA)

Responsive institutional website for a Massachusetts remodeling company.
Administrative dashboard for content and project management.
TypeScript, Next.js, Tailwind CSS, MongoDB, and AWS hosting.
i18n support and Google sign-in for the reviews acquisition flow.

Mince Joias

Full Stack Engineer · Freelance

Aug 2023 – Sep 2023 · Remote

Jewelry e-commerce with Next.js covering catalog, cart, and purchase flow.
Client state with Zustand and UI with Tailwind CSS.
MongoDB persistence and AWS hosting.
Focus on storefront performance and conversion flow.
End-to-end freelance delivery of the digital storefront.

Education and courses

Academic background and continuous learning in technology

UNIVALI

Technologist in Systems Analysis and Development

Mar 2025 – Jun 2027 (in progress)

Curriculum focused on software engineering, architecture, and systems integration.
Combining professional full-stack practice with academic depth.
Emphasis on microservices, databases, and web/mobile development.

Rocketseat

Full Stack Specialization

2023

Mastery of Node.js, React and advanced TypeScript
Building RESTful APIs and microservices
Optimization techniques and cloud deployment

OneBitCode

Full Stack JavaScript Training

2022

Modern JavaScript (ES6+) and design patterns
Full-stack application development
Clean Code and SOLID principles

Harvard CS50

Computer Science

2021

Fundamental algorithms and data structures
C, Python languages and AI concepts
Development of logical reasoning and complex problem solving

UDEMY

Complementary Courses

Various

UI/UX Design with Figma and prototyping
React Native and mobile development
AWS fundamentals and cloud computing

About me

Tech Lead and full stack developer, with work in edtech, SaaS, and fintech. I drive architecture decisions and stay with the product until it ships, using TypeScript, NestJS, Next.js, and React Native. I like multi-tenant systems, code the team can maintain, and talking to the people who run the business — always careful with client confidentiality.