# Evandro Fonseca Junior

**Software engineer building custom systems, apps and integrations.** Backend-focused with Node.js, NestJS, TypeScript, Python and PostgreSQL, and hands-on work with AI agents and MCP tooling.

[Portfolio](https://evandro.dev.br) · [LinkedIn](https://www.linkedin.com/in/evandrodevbr/) · [Email](mailto:evandrofonsecajunior@gmail.com) · [WhatsApp](https://wa.me/5547992742365)

![Node.js](https://img.shields.io/badge/Node.js-5FA04E?logo=nodedotjs&logoColor=white)
![TypeScript](https://img.shields.io/badge/TypeScript-3178C6?logo=typescript&logoColor=white)
![NestJS](https://img.shields.io/badge/NestJS-E0234E?logo=nestjs&logoColor=white)
![Python](https://img.shields.io/badge/Python-3776AB?logo=python&logoColor=white)
![PostgreSQL](https://img.shields.io/badge/PostgreSQL-4169E1?logo=postgresql&logoColor=white)
![Docker](https://img.shields.io/badge/Docker-2496ED?logo=docker&logoColor=white)

## What I do

I build software end to end: understanding the problem, choosing the trade-offs, modeling the data, writing the APIs and the interfaces, testing, deploying and following it in production.

- **Custom systems and apps**: web applications, mobile apps and internal tools, from discovery to production.
- **Integrations**: REST APIs, third-party services and IoT devices talking to the rest of the stack.
- **Backend engineering**: API design, data modeling, authentication and authorization, automated tests, CI/CD.
- **AI and agents**: MCP servers and agent tooling, mostly local-first and self-hosted.
- **Diagnostics**: performance, security and maintainability reviews of existing systems.

Five years of software work, with a longer background in hardware and infrastructure, which helps when a problem leaves the application layer. Based in Garuva, Santa Catarina, Brazil (UTC-3), working remotely. Open to backend engineering roles and to technical collaborations.

## Selected projects

### AI and agent tooling

- **[PiAgentUI](https://github.com/evandrodevbr/PiAgentUI)**: desktop and web workspace for AI coding agents, with streaming sessions, MCP and skills panels, terminal and file explorer (React 19, TypeScript, Vite, Tauri 2, GPL-3.0).
- **[GeminiNexus](https://github.com/evandrodevbr/GeminiNexus)**: multi-account gateway for Gemini and Claude that exposes OpenAI- and Anthropic-compatible endpoints, with SSE streaming, usage analytics and credentials kept in the OS keychain (Electron, React 19).
- **[orelhIA](https://github.com/evandrodevbr/orelhIA)**: local PT-BR audio transcription MCP server on Parakeet TDT, with LRU cache, VAD, metrics, SSRF protection and automated tests (Python, Docker, MIT).
- **[latebra](https://github.com/evandrodevbr/latebra)**: self-hosted MCP server for private web access, search and extraction, with a three-layer anti-bot evasion pipeline, TLS impersonation, proxy rotation and a pytest suite covering the pipeline, proxy manager and stealth layers (Python, MIT).
- **[dev-workflows](https://github.com/evandrodevbr/dev-workflows)**: code review workflows shipped as agent skills, covering frontend, backend, architecture and security with explicit verification steps (MIT).
- **[oh-my-pi-telegram](https://github.com/evandrodevbr/oh-my-pi-telegram)**: Telegram adapter for the Oh My Pi coding agent, so a live terminal session can be driven from a private chat (TypeScript, Node 22).
- **[LocalMind](https://github.com/evandrodevbr/LocalMind)**: mobile chat client for models served by LM Studio on the local network, with no cloud and no API key (React Native, Expo).

### Web apps and developer tools

- **[nutriscan](https://github.com/evandrodevbr/nutriscan)**: nutrition platform over Open Food Facts (2M+ products), with barcode search, Nutri-Score and NOVA filters, multi-layer cache and offline support (Next.js, TypeScript, Prisma). [Live demo](https://nutriscan.evandro.dev.br)
- **[as-servicos](https://github.com/evandrodevbr/as-servicos)**: institutional site for an engineering company, with a procedural Three.js scene that follows the page scroll (Next.js 16, React 19, TypeScript).
- **[Downloader](https://github.com/evandrodevbr/Downloader)**: ephemeral download proxy that fetches files on a VPS into short-lived sessions and serves them to the browser, with SSRF protection (Fastify, React).
- **[cursorAI_install.sh](https://github.com/evandrodevbr/cursorAI_install.sh)**: Bash script that installs, repairs and removes the Cursor IDE on Linux, choosing AppImage, DEB or RPM from the detected distribution and architecture (MIT).
- **[bthaven](https://github.com/evandrodevbr/bthaven)**: native Windows 11 Bluetooth device and audio hub in C#, developed probe-first, so features land only after the underlying Windows behavior is demonstrated with code (MIT).

## Professional work

Part of my work lives in private repositories. The scope, without the code:

- Backend and integrations for the web and mobile applications that support Apolo Energia's internal routines, including IoT device integration and operations dashboards for renewable energy processes.
- A modular NestJS platform (TypeScript, PostgreSQL, Drizzle ORM) split into 8+ isolated domains, with OpenAPI documentation, S3-compatible storage, health checks and automated tests with coverage thresholds of 80% of lines and 70% of branches.
- An offline-first TypeScript SDK with auth, sync, media and transaction modules, including retry with backoff, dead-letter handling and SHA-256 deduplication.
- E-commerce systems with ACID inventory transactions, separate customer and admin authentication and relevance-ranked product search.
- At Innovo (December 2024 to February 2025): Angular front-end components and Node.js back-end logic over PostgreSQL and MySQL, internal libraries and maintenance of legacy systems.

## Stack

| Area | Technologies |
| --- | --- |
| Languages | TypeScript, JavaScript, Python, SQL, Bash, C# |
| Backend | Node.js, NestJS, Fastify, Express, REST APIs, OpenAPI, PHP, Laravel |
| Frontend and mobile | React, Next.js, Astro, React Native, Expo, Tailwind CSS |
| Data | PostgreSQL, MySQL, SQLite, MongoDB, Prisma, Drizzle ORM |
| Infrastructure | Docker, Linux, S3-compatible storage, CI/CD, Firebase |
| Quality and security | Jest, Vitest, pytest, Playwright, OAuth2, JWT, RBAC, Zod |

## Contact

Open to backend engineering roles, technical collaborations and conversations about architecture, APIs and reliable systems. The fastest way to reach me is [email](mailto:evandrofonsecajunior@gmail.com) or [LinkedIn](https://www.linkedin.com/in/evandrodevbr/).

<div align="center">
  <img src="https://github-profile-summary-cards.vercel.app/api/cards/profile-details?username=evandrodevbr&theme=transparent" alt="Evandro's GitHub activity overview" />
</div>