Johann Valenteros personal portfolio

Johann Valenteros

Cybersecurity & information systems. I build small, simple tools and contribute to open source.

About

Undergraduate Student at University of Missouri - St. Louis

I work mostly in the open, small security utilities, encryption tools, and the occasional web build. I care about simple and easy to read code, careful detail, and learning by making mistakes.

154
Contributions
6
Projects
13
Repositories
Selected Works

A Python application for encrypting and decrypting files using industry-standard cryptographic algorithms. A study in cryptographic principles and secure programming.

Highlights
  • Multiple algorithms (AES, RSA) with secure key generation
  • File integrity verification via checksums
  • Clean CLI and detailed logging / error handling
PythonCryptographySecurity

A web app for encoding and decoding text across classic ciphers. Originally built with vanilla JS and Tailwind, later rebuilt with React + Vite for a modular, modern stack.

Supported ciphers
  • ROT13, Caesar, Vigenère
  • Atbash, Rail Fence, Beaufort
  • Real-time character & word count
ReactViteTailwindJavaScript

A command-line tool that scores password strength against length, character variety, and common patterns — a small collaboration grounded in basic security principles.

What it does
  • Checks length and use of upper / lower / number / symbol
  • Returns a strength score and recommendation
  • Follows safe password-handling practices
BashSecurityCommand-line

A browser-based generator for strong, random passwords. Everything runs client-side — passwords are never sent over the network.

Features
  • Adjustable length (8–128) and character sets
  • Strength indicator and one-click copy
  • Uses the Web Crypto API for secure randomness
HTMLCSSJavaScript

A responsive portfolio built from scratch with vanilla web technologies — a focus on minimal design, motion, and accessibility. (You're looking at it.)

Approach
  • Hand-written HTML, CSS & JavaScript, no frameworks
  • Scroll-triggered reveals and a morphing intro
  • Responsive, keyboard-navigable, reduced-motion aware
HTMLCSSJavaScript
Skills

Development

  • HTML & CSS
  • JavaScript
  • Python
  • Java
  • Node.js
  • Bash
  • C#
  • Git
  • GitHub
  • GitLab

Design

  • UI / UX
  • Tailwind CSS
  • Typography
  • Photoshop
  • Illustrator
AI Workflow

Utilizing AI-assistant workflow, hand-verified. I stay accountable for every line.

It's no suprise that AI has dominated most front and backend roles, I utilize AI-assisted development to ship clean, responsive websites while keeping the design authorship, debugging, manual deployment, and quality control in my own agency. I scrutinize and peruse every change by hand, I also trace and fix errors myself, inspecting the console, and testing edge cases, and I can explain in-depth every component, every CSS choice, and the reasoning behind each one.

AI Tools

  • Claude Code
  • Codex
  • VSCode w Claude
  • JetBrains Suite

Backend & Data

  • PostSQL
  • Insomnia API
  • Server & databases
Experience
Healthcare Simulation & Information Systems Assistant
University of Missouri–St. Louis · Part-time
St. Louis, Missouri · On-site
Jan 2026 — Present

Supported medical simulation equipment used in healthcare education and training environments. Assisted with equipment setup, troubleshooting, and organization.

Education
B.S. Cybersecurity — Information Systems & Technology
University of Missouri–St. Louis
Transferred Fall 2025
Expected 2027
A.A.S. Cybersecurity
St. Louis Community College
GPA 3.75 · Cum Laude
2025
Certifications
AWS Certified Cloud Practitioner
Amazon Web Services (AWS)
Valid through May 2028
May 2025
AWS Academy Graduate — Cloud Foundations
Amazon Web Services (AWS)
May 2025
CCNA: Introduction to Networks
Cisco
Mar 2024
Introduction to Cybersecurity
Cisco
Nov 2023
Contact

Open to opportunities and good conversations.

connisquer@gmail.com