Evandro Fonseca Junior

Software engineer building custom systems, apps and integrations — backend-focused, with hands-on work in AI agents and MCP tooling.

Projects · Professional work · Stack · Portfolio · LinkedIn · 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 (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: local PT-BR audio transcription MCP server on Parakeet TDT, with LRU cache, VAD, metrics, SSRF protection and automated tests (Python, Docker, MIT).
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: code review workflows shipped as agent skills, covering frontend, backend, architecture and security with explicit verification steps (MIT).

Web apps and developer tools

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
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: 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.

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