In productionVol. I · 2026 Edition

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Ciélio QueirozPortfolio · Frontend & DataSantana do Araguaia · PA
Vol. ICiélio Queiroz
PT
§ 01 — Introduction
Santana do Araguaia – PA
07/02/2026

.

Front-end developer and data enthusiast — writing software after fifteen-plus years translating numbers into spreadsheets.

Summary

React, Next.js, TypeScript · Power BI, SQL, Python · Automation with n8n. Learning in public since 2024.

LinkedInGitHubInstagram
Contact
◆ React · Next.js · TypeScript15+ years · finance & admin◆ Power BI · SQL Server · Exceln8n · ChatGPT · Power Apps◆ Pará — Brazillearning in public
◆ React · Next.js · TypeScript15+ years · finance & admin◆ Power BI · SQL Server · Exceln8n · ChatGPT · Power Apps◆ Pará — Brazillearning in public

§ 02

Aboutme.

I'm Jaciélio (Ciélio) Queiroz — a business administrator by training with 15+ years in administrative and financial management, now diving into web development and data science.

My path connected accounts payable/receivable, cash flow and tax control to projects involving React, Power BI, SQL and n8n automation — always chasing leaner processes and real results.

Today I build modern interfaces with React/Next.js and analytical dashboards, pairing business insight with the ability to ship software that solves real problems.

“Every spreadsheet I automated taught me that good code is, in the end, people saving time.”
— Ciélio Queiroz, 2026
◇ Frontend◇ Data analysis◇ Automation◇ Management◇ Continuous learning

§ 03

Selected work.

Case 01

Gabarito AI

CodeLive demo
Context
Studying for Brazilian civil-service exams means turning a dense, dozens-of-pages syllabus into an actionable study plan — manual, repetitive work that is easy to abandon.
What I built
An AI study console: upload the official syllabus as a PDF and the app generates a study plan, spaced-repetition flashcards (Leitner method) and annotated practice questions using Claude, with auth and persistence on Supabase.

Stack

Next.js 16 · TypeScript · Supabase · Claude API · Vercel

Takeaway →Real production AI: structured prompts, per-request cost awareness and honest loading states.

Case 02

Investment Calculator

CodeLive demo
Context
Fifteen years of cash-flow management taught me that compound interest decides every plan — yet most calculators hide the assumptions behind the math.
What I built
A Brazilian investment simulator: compound interest with monthly contributions, product comparison, goal planning and real-time market data (B3, crypto, FX) — all in the browser, no backend.

Stack

React · TypeScript · Vite

Takeaway →Numeric precision in JavaScript, public API consumption and a serverless front-end architecture.

Case 03

This portfolio

Code
Context
A career-changing developer needs to prove competence without industry job history — so the site itself becomes the technical argument.
What I built
A static Next.js one-pager with a single-source theme (one file drives the site, OG banner and manifest), a PDF résumé generated in the browser, a live repository showcase via the GitHub API, a PT/EN version and a three.js 3D scene.

Stack

Next.js 15 · React 19 · TypeScript · Tailwind · three.js · @react-pdf/renderer

Takeaway →Performance as a requirement (LCP, bundle, reduced-motion) and end-to-end AA accessibility.

Live archive

List updated in real time via the GitHub API. Pinned first, then by push date.

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§ 04

Tools & craft.

Index · 22 items

01 / 05

Frontend

9 technologies

  • 01HTML5
    ◆ in use
  • 02CSS3
    ◆ in use
  • 03JavaScript
    ◆ in use
  • 04TypeScript
    ◆ in use
  • 05React
    ◆ in use
  • 06Next.js
    ◆ in use
  • 07Tailwind CSS
    ◆ in use
  • 08Material UI
    ◆ in use
  • 09Vite
    ◆ in use

02 / 05

Backend & Languages

2 technologies

  • 01Node.js
    ◆ in use
  • 02Python
    ◆ in use

03 / 05

Data & BI

4 technologies

  • 01Power BI
    ◆ in use
  • 02SQL Server
    ◆ in use
  • 03Jupyter
    ◆ in use
  • 04Excel
    ◆ in use

04 / 05

Automation & AI

4 technologies

  • 01n8n
    ◆ in use
  • 02Power Apps
    ◆ in use
  • 03ChatGPT / IA
    ◆ in use
  • 04Claude Code
    ◆ in use

05 / 05

Tooling

3 technologies

  • 01Git
    ◆ in use
  • 02GitHub
    ◆ in use
  • 03VS Code
    ◆ in use

§ 05

Credentials & education.

Archive · 49 certificates

University degree

Bachelor's in Business Administration

UNOPAR · 2022

01 / 04

Programming

18 certificates

  • 01Formação Full Stack JavaScript (HTML, CSS, JS, React, Next, Node, Mongo, Git)
    Thiago M. Medeiros — 50h✓
  • 02Responsive Web Design
    freeCodeCamp✓
  • 03Santander Bootcamp Dev 2024
    Santander / DIO✓
  • 04Cibersegurança — Nivelamento (80h)
    Hackers do Bem · SENAI/Softex/RNP✓
  • 05Cibersegurança — Básico (64h)
    Hackers do Bem · SENAI/Softex/RNP✓
  • 06HTML5 e CSS3
    Hora de Codar✓
  • 07Programação para Internet com JavaScript
    Hora de Codar✓
  • 08Lógica de Programação
    Hora de Codar✓
  • 09Estrutura de Dados e Algoritmos
    Hora de Codar✓
  • 10Git e GitHub
    Hora de Codar✓
  • 11GitHub
    EduLiv Educação✓
  • 12VS Code — Instalação e Configuração
    Hora de Codar✓
  • 13VS Code — Diploma Digital
    EduLiv Educação✓
  • 14Instalando o Visual Studio e SDK
    Microsoft (curso livre)✓
  • 15Trybe
    Trybe✓
  • 16Hora do Código
    CODE.org✓
  • 17LGPD — Primeiras Noções
    Hora de Codar✓
  • 18SQL Server na Prática
    Curso Online✓

02 / 04

Data & BI

13 certificates

  • 01Power BI para Business Intelligence e Data Science
    Preditiva✓
  • 02Fundamentos de Data Science e IA
    Preditiva✓
  • 03Power BI — Dashboard de Fluxo de Caixa
    LinkedIn Learning✓
  • 04Power BI — Dashboard de RH
    LinkedIn Learning✓
  • 05Power BI
    Fundação Bradesco✓
  • 06Analista de Dados com Power BI
    EduLiv Educação✓
  • 07Excel Extremo
    EduLiv Educação✓
  • 08Jupyter
    EduLiv Educação✓
  • 09Python Extremo
    EduLiv Educação✓
  • 10Python para Não-Programadores
    LinkedIn Learning✓
  • 11DBA — Banco de Dados
    Fundação Bradesco✓
  • 12Dicas Rápidas do Excel
    LinkedIn Learning✓
  • 13Tabelas Dinâmicas no Excel
    LinkedIn Learning✓

03 / 04

AI & Automation

9 certificates

  • 01ChatGPT para Desenvolvedores
    Hora de Codar✓
  • 02n8n em 1 hora
    Hora de Codar✓
  • 03Agente de IA no n8n
    Hora de Codar✓
  • 04IA Generativa para Finanças e Contabilidade
    LinkedIn Learning✓
  • 05IA Aplicada a Finanças
    Curso Online✓
  • 06IA na Prática
    Fundação Bradesco✓
  • 07Power Apps — Formação Básica
    LinkedIn Learning✓
  • 08Power Apps Expert
    Viscari✓
  • 09IA para Comunicação Corporativa
    LinkedIn Learning✓

04 / 04

Business & Management

9 certificates

  • 01Analista Financeiro
    Curso Online✓
  • 02Análise Financeira
    Curso Online✓
  • 03Demonstrativo Financeiro
    Curso Online✓
  • 04Fluxo de Caixa
    Curso Online✓
  • 05Gestão Lucrativa — Vende-C
    Curso Online✓
  • 06Colaboração no Microsoft 365
    LinkedIn Learning✓
  • 07Inglês para Negócios — Pronúncia para Nativos de Português
    LinkedIn Learning✓
  • 08Língua Inglesa I
    UNOPAR✓
  • 09Língua Inglesa II
    UNOPAR✓

Certificate titles are kept in their original Portuguese.

§ 06

Living spreadsheets.

Financial models I build in Excel — recreated here as editorial HTML. Illustrative data.

Case 01 · Corporate income statement

Income Statement — Nexus Corporação S.A.

Fiscal year 2024

Gross margin

36,9 %

EBITDA margin

18,9 %

Net margin

9,3 %

Revenue YoY

+15,6 %

← Swipe to see more →

AccountAmount (R$)Vertical %YoY %
Gross Sales RevenueR$95,840,000100.0%+15.6%
(–) Deductions & Taxes(R$12,200,000)-12.7%+14.2%
Net RevenueR$83,640,00087.3%+15.8%
(–) Cost of Goods Sold(R$48,320,000)-50.4%+13.1%
Gross ProfitR$35,320,00036.9%+19.6%
(–) Operating Expenses(R$19,840,000)-20.7%+9.2%
EBITDAR$18,120,00018.9%+22.4%
(–) Depreciation & Amortization(R$2,640,000)-2.8%+6.1%
EBITR$15,480,00016.2%+25.5%
Financial Result(R$1,140,000)-1.2%-8.3%
(–) Income Taxes(R$5,430,980)-5.7%+28.8%
Net IncomeR$8,909,0209.3%+31.8%

Source: model spreadsheet · illustrative data · vertical and YoY analysis calculated over gross revenue.

Case 02 · Household cash flow

Household Budget Tracker

January – June 2026

Income

R$98,445

Expenses

R$87,827

Net balance

R$10,618

% committed

89.2%

MonthIncomeExpensesBalanceCommittedStatus
JanuaryR$15,735R$13,967R$1,768
88.8%
positive
FebruaryR$16,120R$14,240R$1,880
88.3%
positive
MarchR$15,980R$15,320R$660
95.9%
watch
AprilR$16,540R$13,870R$2,670
83.9%
positive
MayR$17,200R$14,590R$2,610
84.8%
positive
JuneR$16,870R$15,840R$1,030
93.9%
positive
Period totalR$98,445R$87,827R$10,61889.2%positive

Source: “Household Budget 2026” spreadsheet · built in Excel · automated dashboard.