Ronis@ronisninja
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NowSoftware EngineerFits(formerly FitBank) · since Oct 2026

Ronis

Full-Stack & AI Engineer, C#/.NET

Portrait of Ronis with eyes closed, in red light

Senior Software Engineer with 18+ years of experience. Strong in backend development and scalable architecture — currently focused on C#/.NET — plus full-stack work with TypeScript, React and Node.js. AI is part of how I build software: agentic coding in my daily workflow and LLMs integrated into products.

Email
valdir@ronis.com.br
Phone
+55 85 99929-2118
Profiles
LinkedInGitHubWhatsApp
Based in
Fortaleza, Ceará — Brazil
Time zone
GMT-3 (Brasília)
Self-taught
since Aug 1996
Get in touchDownload CV (PDF)

v26a is the numeronym of my full name, like k8s and i18n: v + 26 letters + a. Between the V and the A fits the entire alphabet.

Experience

8 roles · 2007 – today

  1. Fits · now
  2. PliQCX · 2024–26
  3. Estácio de Sá · 2024–26
  4. Freelancer · 2020–24
  5. Plante Amor · 2020
  6. Grupo Biagi · 2019–20
  7. Raízes Soluções · 2019
  8. Freelancer · 2008–19
  9. Hipermercadinho Local · 2007–08
  10. Self-taught since Aug 1996
Timeline · columns A–Z = 2001–2026
  • Work
  • Current
  • Education
  • Self-taught

Oct 2026 – PresentFortaleza, CE

Software Engineer

Fits (formerly FitBank)

Payments infratech.

  • C#
  • .NET

Aug 2024 – Sep 20262 yrs 2 mosFortaleza, CE

Full-Stack & AI Engineer

PliQCX

  • Worked across the full stack with the autonomy to propose architecture decisions and steer the technical direction in line with business goals.
  • Modernized legacy systems into .NET Core backend services, built for observability and long-term maintainability.
  • Designed REST/gRPC APIs and asynchronous workers (Quartz.NET, Background Workers) built to handle growing load.
  • Integrated external services and automated critical workflows with well-defined contracts and failure handling, on a foundation of Clean Architecture, SOLID and continuous code review.
  • Adopted agentic coding (Claude Code, MCP) and integrated AI/LLMs into product features, with well-defined contracts, failure handling and guardrails for model limitations.
  • .NET
  • .NET Core
  • C#
  • REST
  • gRPC
  • Quartz.NET
  • Background Workers
  • PostgreSQL
  • Entity Framework
  • Dapper
  • Docker
  • Git
  • Azure DevOps
  • AI/LLMs
  • Agentic Coding
  • Claude Code
  • MCP

Jul 2020 – Jul 20244 yrs 1 moHybrid (Fortaleza, CE)

Backend & Architecture Consultant

Freelancer

  • Architected and built backend services for multiple clients in Java/Spring Boot, Node.js and PHP/Laravel, with scalability as the priority.
  • Modernized legacy PHP applications into modular, sustainable architectures, migrating part of them to Laravel.
  • Designed data models and access strategies in MySQL and PostgreSQL to reduce performance bottlenecks in production.
  • Defined REST and GraphQL API standards, including versioning and maintenance, balancing delivery speed and technical quality.
  • Standardized environments and workflow with Docker and Git for reproducible builds across projects.
  • Java
  • Spring Boot
  • Node.js
  • PHP
  • Laravel
  • GraphQL
  • REST
  • MySQL
  • PostgreSQL
  • Docker
  • Git

Mar 2020 – Jul 20205 mosSão José do Rio Preto, SP

Full-Stack Developer

Plante Amor/Murau

Show 4 highlights — Full-Stack Developer
  • Built integrations between the TOTVS Protheus ERP and the VTEX IO e-commerce platform, keeping data consistent and traceable.
  • Designed REST APIs in Node.js and TypeScript to sync catalog, prices and orders across separate sales channels.
  • Defined delivery and quality standards that reduced rework in production.
  • Led architecture and end-to-end execution, delivering on a tight deadline.
  • VTEX IO
  • Node.js
  • TypeScript
  • REST
  • WebSockets
  • MongoDB
  • TOTVS Protheus
  • Git

Sep 2019 – Feb 20206 mosSão José do Rio Preto, SP

Full-Stack & DevOps Developer

Grupo Biagi/Boxsupreme.com.br

Show 4 highlights — Full-Stack & DevOps Developer
  • Migrated a legacy system to a more stable backend on AWS EC2 with Docker and PHP, keeping operations running throughout the transition.
  • Optimized SQL queries and indexes in MariaDB/MySQL, improving the performance of transactional flows.
  • Automated operational tasks with shell scripts on Linux and set up monitoring, reducing recurring incidents.
  • Set up the cloud infrastructure on AWS EC2 and Nginx with predictable availability and costs.
  • PHP
  • MariaDB
  • MySQL
  • AWS EC2
  • Docker
  • Linux
  • Nginx
  • Git
  • Shell Script
  • SQL

Apr 2019 – Aug 20195 mosSão José do Rio Preto, SP

Full-Stack Developer & IT Analyst

Raízes Soluções

Show 4 highlights — Full-Stack Developer & IT Analyst
  • Developed and maintained the e-commerce backend in PHP/MySQL, keeping it stable and integrated with external systems via REST.
  • Built REST APIs in PHP/MySQL to automate operational processes.
  • Standardized technical workflows, making the platform simpler to maintain and evolve.
  • Kept operations running with Windows Server/IIS infrastructure and monitoring.
  • PHP
  • MySQL
  • REST
  • Node.js
  • Git
  • Windows Server
  • IIS
  • Networking

Dec 2008 – Feb 201910 yrs 3 mosFortaleza, CE / São José do Rio Preto, SP / Hybrid

IT Consultant & Backend Solutions Developer

Freelancer

Show 4 highlights — IT Consultant & Backend Solutions Developer
  • Modernized legacy systems and built integrations for retail and service companies in Java and PHP.
  • Developed automations that reduced rework and raised operational efficiency.
  • Designed data models and implemented integrations in MySQL, PostgreSQL and SQL Server to support business growth.
  • Kept critical systems running through infrastructure consulting on Windows Server, Linux, networking and hardware.
  • Java
  • PHP
  • MySQL
  • PostgreSQL
  • SQL Server
  • Windows Server
  • Linux
  • Networking
  • Hardware

Oct 2007 – Nov 20081 yr 2 mosFortaleza, CE

IT Manager & Systems Analyst

Hipermercadinho Local

Show 4 highlights — IT Manager & Systems Analyst
  • Administered the PostgreSQL database with backup, recovery and integrity-check routines for the retail operation.
  • Administered the SysPDV point-of-sale system and tax processes, keeping daily operations reliable.
  • Managed the IT infrastructure (Windows Server, network and hardware) to keep the business running.
  • Organized administrative and financial processes around consistent data in PostgreSQL and Excel.
  • SysPDV
  • PostgreSQL
  • SQL
  • Microsoft Excel
  • Windows Server
  • Networking
  • Hardware
  • Backup & Recovery

Skills

Text size = level:ExpertProficientAdvancedIntermediateBeginner

AI & LLMs

  • Agentic Coding (Claude Code) — level 4, Proficient
  • LLMs / Applied AI — level 4, Proficient
  • Anthropic / OpenAI APIs — level 3, Advanced
  • Context Engineering — level 3, Advanced
  • LLM Product Integration — level 3, Advanced
  • Context-Driven Development (CDD) — level 2, Intermediate
  • MCP (Model Context Protocol) — level 2, Intermediate
  • Spec-Driven Development (SDD) — level 2, Intermediate

Languages

  • PHP — level 5, Expert
  • C# — level 4, Proficient
  • Java — level 4, Proficient
  • JavaScript — level 4, Proficient
  • SQL — level 4, Proficient
  • TypeScript — level 4, Proficient

Frameworks & APIs

  • REST — level 5, Expert
  • .NET / ASP.NET Core — level 4, Proficient
  • Laravel — level 4, Proficient
  • Node.js — level 4, Proficient
  • Spring Boot — level 4, Proficient
  • GraphQL — level 3, Advanced
  • WebSockets — level 3, Advanced
  • gRPC — level 3, Advanced

Cloud & DevOps

  • AWS — level 4, Proficient
  • Azure — level 4, Proficient
  • Docker — level 4, Proficient
  • GCP — level 3, Advanced
  • Kubernetes — level 3, Advanced

Databases & ORMs

  • Entity Framework — level 4, Proficient
  • PostgreSQL — level 4, Proficient
  • SQL Server — level 4, Proficient
  • Dapper — level 3, Advanced
  • Doctrine — level 3, Advanced
  • Eloquent — level 3, Advanced
  • Prisma — level 3, Advanced

Soft Skills

  • Focus on production reliability
  • Long-term maintainability
  • Metrics-driven optimization
  • Readability as a maintenance strategy
  • Safe evolution of legacy systems
  • Scalability with architectural clarity
  • Simplifying without sacrificing flexibility
  • Technical decisions aligned with the business

AI & Engineering Practices

For me, AI is about more than productivity: I combine day-to-day agentic coding, LLMs integrated into products, and practices such as Spec-Driven and Context-Driven Development so that people and agents produce consistent code — always with architecture and quality at the core.

Day-to-day agentic coding

I use AI agents (such as Claude Code) built into my development workflow to speed up delivery without compromising on review, standards or quality. The agent acts as a pair programmer for implementation and refactoring; architecture decisions stay with humans.

SDD — Spec-Driven Development

I have been adopting Spec-Driven Development at work: clear specifications guide implementation by both people and AI agents, becoming the source of truth and reducing ambiguity and rework.

CDD — Context-Driven Development

Increasingly part of my work, Context-Driven Development is about engineering the context (memory, rules and documentation) so that AI generates code that follows the project's standards in a predictable, consistent way.

LLMs built into the product

I integrate AI/LLMs directly into products and features, not only into the development workflow. I design the contracts, failure handling and guardrails for model limitations so these features are reliable in production.

Projects

4 projects · 2 featured

Harpa Cristã App

Featured

Native Android app for offline access to the 640 hymns of the Harpa Cristã hymnal, built with React Native:

  • Optimized performance: Local storage with MMKV for instant loading
  • Smart search: Find hymns by number, title or a line of the lyrics
  • Favorites and history: Bookmark hymns and track the most visited ones
  • Accessibility: Adjustable font size, light/dark themes and a responsive interface
  • React Native
  • TypeScript
  • MMKV
  • Android
Code on GitHub: Harpa Cristã App

This Portfolio (ronis.com.br)

Featured

Interactive, responsive digital résumé — the one you are browsing right now — built with Next.js 16 and recently redesigned with AI support (agentic coding):

  • Modern stack: React 19, TypeScript, Tailwind CSS v4
  • AI support: Redesigned with agentic coding, keeping architecture decisions and code review under my control
  • Bilingual: Portuguese and English, with the résumé PDF in each language
  • Performance: SSG with Next.js, image optimization, lazy loading
  • Its own look (v26a): a 26-column grid, variable type, light and dark themes and a hidden terminal
  • Print-friendly: CSS tuned for professional PDF export
  • Complete SEO: Meta tags, Open Graph, sitemap, robots.txt
  • Next.js 16
  • React 19
  • TypeScript
  • Tailwind CSS v4
  • Agentic Coding
Open the site: This Portfolio (ronis.com.br)

Random Numbers with Exclusions

npm library for generating random numbers with fine-grained exclusion control:

  • Customizable generation: Configurable ranges with multiple options
  • Flexible exclusions: Single numbers, ranges or arrays of exclusions
  • Zero dependencies: Lightweight and fast
  • TypeScript ready: Full typings for a better developer experience
  • Use cases: Raffles, games, statistical sampling
  • JavaScript
  • TypeScript
  • npm
Code on GitHub: Random Numbers with Exclusions

str-async-replace

TypeScript utility for asynchronous string replacement with Promise support:

  • Async API: Replace with native async/await
  • API integration: Fills placeholders with data from external requests
  • Pattern matching: Supports RegEx and string literals
  • Type-safe: Fully typed in TypeScript
  • Use cases: Dynamic templates, markdown processing, internationalization
  • TypeScript
  • JavaScript
  • npm
  • Async/Await
Code on GitHub: str-async-replace

Testimonials

LinkedIn recommendations

Ronis is a one-of-a-kind professional with an outstanding product vision. He always brings his point of view to important discussions and backs it up with experiments and articles. It was a real pleasure to work alongside him and share experiences and challenges. He has my recommendation, and my thanks for all his work and everything he brought to the team!

Guilherme NojosaSolution Architect | Tech LeadDirect managerTranslated from Portuguese

Even though we worked together for a short time, it was clear that Ronis is very professional and a genuinely nice guy. He is patient when passing on what he knows, has a lot of experience and broad knowledge. I was lucky to share that time and learn a lot. Wishing you success wherever you go!

Thallys FreitasSoftware EngineerTeammate at PliQCXTranslated from Portuguese

An excellent person and professional, very experienced as a full-stack developer, with a strong command of the industry's main stacks. Rooting for you on your AWS certification. All the best, Valdir!

Aglayrton JuliãoBack-end Developer | Python | AIFormer instructorTranslated from Portuguese

Education

Degree + continuous learning

Jan 2024 – Jul 2026

Undergraduate Degree in Systems Analysis and Development (Tecnólogo)

Estácio de Sá

Focused on software architecture, databases, agile methodologies and full-stack development

Aug 1996 – Present

Software Development and Web Technologies

Self-taught

Continuous learning through online courses, official documentation, hands-on projects and developer communities

Certifications

35 certificates · Alura 18 · Descomplica 7 · Udemy 7 · DevMedia 2 · Let's Code & iFood 1

Show all 35

2024

2023

2021

Course titles are kept in the original Portuguese.

Contact

Connect with me on social media or send me an email. I'm always open to exchanging ideas and collaborating.

Email
valdir@ronis.com.br
Phone
+55 85 99929-2118
Based in
Fortaleza, Ceará — Brazil
Time zone
GMT-3 (Brasília)
Handle
@ronisninja
Résumé
Download PDF

Get in touch

Send me a message and let's talk.

The form needs JavaScript. Write to me directly at valdir@ronis.com.br.