# Evandro Fonseca Junior

**Backend Software Engineer | Node.js · NestJS · TypeScript · Python · PostgreSQL**

I build reliable backend systems, APIs and integrations, with hands-on experience taking products from technical discovery and architecture through implementation, testing, deployment and production support.

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

## About me

I'm a backend developer with 5+ years of software experience and a long-standing background in hardware and infrastructure. That combination helps me investigate problems beyond application code and design for reliability from the start.

In the projects under my technical responsibility, I have made architecture and implementation decisions end to end: understanding business goals, choosing trade-offs, modeling data, building APIs, automating tests and delivery, and following the system in production. I value simple solutions, clear communication and ownership without losing the humility to ask, validate and learn.

I'm currently focused on **Backend Developer / Backend Software Engineer** opportunities where I can contribute with autonomy, responsibility and consistent delivery.

## Production work

Some recent professional systems are private, but their architecture and outcomes can be discussed publicly:

- Owned the architecture and delivery of a web, mobile and IoT ecosystem using NestJS, Next.js, React Native/Expo, TypeScript, Python and PostgreSQL.
- Designed a modular NestJS platform with **8+ isolated domains**, full OpenAPI documentation, S3-compatible storage, health checks and automated tests with reported coverage above **80% of lines and 70% of branches**.
- Built a reusable offline-first TypeScript SDK with auth, sync, media and transaction modules, including **46+ integration tests**, retry/backoff, dead-letter handling and SHA-256 deduplication.
- Implemented an e-commerce search engine with scoring across **7 dimensions**, ACID inventory transactions, isolated customer/admin authentication and a layered shipping fallback strategy.
- Collaborated on Angular and Node.js legacy modernization, internal libraries and business-rule implementation at Innovo.

## Core stack

| Area | Technologies |
| --- | --- |
| Backend | Node.js, NestJS, TypeScript, Python, REST APIs, OpenAPI |
| Data | PostgreSQL, SQL, Drizzle ORM, Prisma ORM, SQLite |
| Cloud & infrastructure | Docker, AWS S3, Linux, Cloudflare, CI/CD |
| Quality & security | Jest, Vitest, Playwright, OAuth2, RBAC, JWT, Zod |
| Additional experience | Offline-first systems, IoT/Edge, observability, computer vision, React Native |

## Selected projects

### [PiAgentUI](https://github.com/evandrodevbr/PiAgentUI)

Desktop and web workspace for AI coding agents, with streaming sessions, MCP and skills panels, terminal, file explorer and a Tauri desktop application. Built with React 19, TypeScript, Vite and Tauri 2.

### [Gemini Nexus](https://github.com/evandrodevbr/GeminiNexus)

Multi-account desktop gateway for Gemini and Claude. Provides OpenAI- and Anthropic-compatible APIs, SSE streaming, account switching, traffic observability and encrypted credential storage.

### [orelhIA](https://github.com/evandrodevbr/orelhIA)

Local and privacy-oriented PT-BR audio transcription server for MCP agents. Built with Python, Docker and Parakeet TDT, with caching, metrics, SSRF protection and automated tests.

### [NutriScan](https://github.com/evandrodevbr/nutriscan)

Nutrition information platform using Next.js, TypeScript and Prisma. Integrates a collaborative dataset covering 2M+ products and 100+ countries, with advanced filters, layered caching and offline support.

### [latebra](https://github.com/evandrodevbr/latebra)

Self-hosted Python MCP server for private and resilient web access, search and extraction, with layered fallbacks, proxy support, observability and an extensive automated test suite.

## Contact

I'm 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)

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