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Luiz Jelonschek
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    • SetupBarato — Case study
    • Open website: SetupBarato
    • MiranteSEO — Case study
    • Open website: MiranteSEO
    • VitrineBeauty — Case study
    • Open website: VitrineBeauty
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↑ ↓ to navigate · Enterjelonschek.com
PT, Ler em português

Open to opportunities and collaborationsDois Vizinhos, Brazil GMT-3

I build C#/.NET backends and ship products that run in production.

I'm Luiz Eduardo Jelonschek, a systems analyst at Nootech (opens in a new tab), where I work on marketplace integrations, fiscal automation and point-of-sale software. On my own, I built and run SetupBarato, MiranteSEO and VitrineBeauty, from database to deploy.

See the products

Systems in production

3 of 3 live

Public numbers from each site, as of Oct 2026

01Products

Three products, from zero to live.

I built and run each one on my own: product, data collection, backend, front-end and infrastructure. All of them are live and serve real users.

SetupBarato

Hardware price comparison

Compares hardware prices across 35 stores and tells you if today’s price is really good.

SetupBarato compares about 95k products across 35 Brazilian stores and judges today’s price against the last 90 days of history. It also builds a compatible PC for a given use and budget, and a browser extension shows the verdict right on the store’s page.

products tracked
~95k
Brazilian stores
35
between collection rounds
90 min

Live since Jun 2026Next.js · TypeScript · PostgreSQL · Tailwind CSS · Docker

Read the case study: SetupBaratosetupbarato.com.br(opens in a new tab)

MiranteSEO

SEO dashboard with MCP

Brings Search Console, GA4 and Core Web Vitals together and shows what to act on first.

MiranteSEO brings Search Console, Google Analytics 4 and Core Web Vitals into one dashboard with comparable history and ranked opportunities. A 49-rule crawler covers technical SEO, and an MCP connector with 80+ tools lets Claude, ChatGPT and Cursor query the same data.

MCP connector tools
80+
technical crawler rules
49
free tools, no signup
7

Live since Aug 2026Next.js · TypeScript · PostgreSQL · MCP · Docker

Read the case study: MiranteSEOmiranteseo.com.br(opens in a new tab)

VitrineBeauty

Beauty price comparison

Compares the same cosmetic across 18 stores, by shade, by size and by price per ml.

VitrineBeauty matches the same cosmetic by barcode, shade by shade and size by size, across 18 Brazilian stores. It shows the price per ml or per gram and keeps its own price history to tell you whether to buy now or wait.

offers compared
485k
products with live offers
116k
stores read every 3 hours
18

Live since Sep 2026Next.js · TypeScript · PostgreSQL · Prisma · Tailwind CSS

Read the case study: VitrineBeautyvitrinebeauty.online(opens in a new tab)

02Experience

Where I work and what I study.

  1. 2025 — present

    Systems Analyst · Nootech Sistemas(opens in a new tab)

    C#/.NET backend for a white-label ERP, point-of-sale, delivery and payments platform with 350+ resellers and 7,000 businesses served. I work on marketplace integrations, fiscal automation and point-of-sale improvements.

    • C#
    • .NET
    • SQL Server
    • REST APIs

  2. 2026 — present

    Founder and developer · SetupBarato · MiranteSEO · VitrineBeauty

    Three products of my own, from database to deploy: price collection across dozens of stores, data dashboards and an MCP server for AI assistants.

    • TypeScript
    • Next.js
    • PostgreSQL
    • Docker

  3. In progress

    B.Sc. in Software Engineering · UTFPR(opens in a new tab)

    Federal University of Technology – Paraná. Academic projects such as Rota Viva, a gamified tourism platform for Dois Vizinhos.

  4. 2024

    Pentest from Zero to Professional · Solyd Offensive Security

    Offensive security course, with Python applied to penetration testing.

03Projects

Other projects, studies and experiments.

All repositories on GitHub(opens in a new tab)

04About

Backend as the foundation, product as the goal.

Early on, technology became the place where I like to build things and solve problems. At Nootech I work on software that thousands of businesses use at the checkout every day, and the goal is always the same: make it more reliable, efficient and closer to how customers actually operate.

Outside work, I build my own products. I like the hard part that stays hidden: collecting data from dozens of stores, recognizing the same product across them, keeping the history and turning all of it into a simple answer for the person on the other side.

I study Software Engineering at UTFPR and, in my spare time, offensive security.

Now

  • Building MeuFPS, a Windows FPS meter in Rust and Tauri
  • Improving SetupBarato, MiranteSEO and VitrineBeauty
  • Studying Software Engineering at UTFPR
  • Learning penetration testing and offensive security

Toolbox

Backend
C#, .NET, ASP.NET MVC, Node.js, Python, Rust, C
Data
SQL Server, PostgreSQL, Prisma, SQLite
Front-end
TypeScript, React, Next.js, Tailwind CSS
Infra
Docker, Cloudflare, Vercel, Linux, Git
Security
Kali Linux, Nmap, Burp Suite, Wireshark

05Contact

Let's talk.

I'm open to opportunities, collaborations and conversations about backend, product and data. Email or LinkedIn is the fastest way to reach me.