# Evandro Fonseca Junior
**Software engineer building custom systems, apps and integrations —
backend-focused, with hands-on work in AI agents and MCP tooling.**
[Projects](#selected-projects) · [Professional work](#professional-work) · [Stack](#stack) · [Portfolio](https://evandro.dev.br) · [LinkedIn](https://www.linkedin.com/in/evandrodevbr/) · [Contact](#contact)
> [!NOTE]
> **Status:** open to backend engineering roles and to technical collaborations.
> Based in Garuva, Santa Catarina, Brazil (UTC-3), working remotely.
## 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.
| Area | What it covers |
| --- | --- |
| **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.
## Selected projects
### AI and agent tooling
- **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).
- **[gemini-nexus](https://git.evandro.dev.br/evandro/gemini-nexus)** (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://git.evandro.dev.br/evandro/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://git.evandro.dev.br/evandro/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://git.evandro.dev.br/evandro/dev-workflows)**: code review workflows shipped as agent skills, covering frontend, backend, architecture and security with explicit verification steps (MIT).
### Web apps and developer tools
- **[nutriscan](https://git.evandro.dev.br/evandro/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)
- **[ASServicos](https://git.evandro.dev.br/evandro/ASServicos)** (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).
- **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://git.evandro.dev.br/evandro/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
> [!NOTE]
> Part of my work lives in private repositories. This is 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.
- Portfolio: [evandro.dev.br](https://evandro.dev.br)
- LinkedIn: [linkedin.com/in/evandrodevbr](https://www.linkedin.com/in/evandrodevbr/)
- Email: [evandrofonsecajunior@gmail.com](mailto:evandrofonsecajunior@gmail.com)
- WhatsApp: [+55 47 99274-2365](https://wa.me/5547992742365)