Jonnel Mendoza

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Full-Stack Developer & Product Designer

Solo developer, UI/UX designer and product manager — building complete digital products from concept to deployment. I design, build and ship full-stack web applications, SaaS platforms, and games end-to-end, handling everything from database architecture and REST APIs to pixel-perfect UI, payment integration and SEO.


Data & Analysis

Analysing and visualising data to surface insights, drive decisions and tell compelling stories with numbers.

Python (Pandas, Seaborn, Matplotlib), SQL, Excel, Tableau, Power BI, Streamlit, Data Visualisation, Statistical Analysis, Dashboard Design, Data Storytelling, EDA, Forecasting, KPI Reporting, AI


Development & Engineering

React, TypeScript, Node.js, Express, PostgreSQL, Drizzle ORM, REST APIs, Clerk Auth, Vite, Tailwind CSS, Framer Motion, HTML, CSS, JavaScript


Design & Product

UI/UX Design, Product Design, Brand Identity, Wireframing, Component Design, Animation, Card & Asset Design, Game Design, User Research


Infrastructure & Growth

Railway, Netlify, GitHub, CI/CD, SEO, Payment Integration (Stripe), Performance Optimisation, Analytics


Soft Skills

Effective Communication, Collaboration, Problem-Solving, Creativity, Attention to Detail, Self-motivated, Adaptability, Continuous Learning

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Portfolio


Full-Stack Web Development & Product Design


Infinite Collectibles — Full-Stack Digital Collectible Card Game

Role: Solo Developer · UI/UX Designer · Product Designer · Game Designer · Card Artist · Tooling Developer

Overview
Infinite Collectibles is a fully original digital collectible card game built entirely solo — 187 hand-designed cards across 6 rarity tiers, a custom pack-opening experience, progression systems, daily engagement loops, an in-game economy and a live platform deployed on Railway and Netlify. Every element of the product — from database schema to card artwork to game design — was conceived, designed and built by one person.

What I Built

Frontend & UI/UX

  • Designed and built the entire UI system from scratch — dark fantasy aesthetic with custom rarity colour system, glassmorphism card frames, animated overlays and a fully responsive layout across all views
  • Built the pack opening experience — animated card reveal sequence with rarity-specific audio feedback, tilt physics, particle effects and cinematic transitions that rival commercial card game experiences
  • Engineered a custom card renderer (CollectibleCard.tsx) with 7 full variant visual presets — Holographic, Prism, Ancient, Phantom, Corrupted, Cursed and Ultra — each with layered canvas animations, shader-style blend modes and real-time effects running at 60fps
  • Built the Variant Builder — an internal dev tool allowing real-time design of card visual presets using a layered compositing system with 40+ canvas effect types, live preview and JSON export
  • Designed 187 original cards — lore, rarity, type, culture, gradients and artwork direction for each entry spanning mythologies and phenomena from over 30 world cultures
  • Built The Codex achievements page, The Altar ritual sacrifice system, The Pyre duplicate burning mechanic, The Path 90-day reward calendar and The Oracle daily trivia system
  • Implemented the Collection, Reliquary and Ascendant leaderboard views with lazy-loading, filtering and rarity-sorted grid layouts
  • Backend & Architecture

  • Designed and built the entire REST API in Node.js/Express with full TypeScript coverage — authentication, pack logic, card serial tracking, user progression, daily systems and achievement triggers
  • Designed the PostgreSQL schema using Drizzle ORM — users, collectibles, pack inventory, altar slots, XP/level, essence balance, streaks, oracle history and global milestone tracking
  • Built a deterministic serial number and edition tracking system — each card has a unique global serial (#1/50, #2/50 etc.) persisted across all users
  • Implemented a weighted pack probability engine with rarity gates, variant chance modifiers, event boosts and a guaranteed Rare+ minimum per pack
  • Built server-side level gating (Lv15 → Altar, Lv20 → Pyre, Lv30 → Resonance, Lv50 → Crucible) with 403 enforcement and locked UI states client-side
  • Implemented The Oracle — a daily trivia system with 50 lore-based questions, streak tracking, essence rewards, achievement triggers and correct-answer reveal logic
  • Built a global milestone system tracking community-wide resonance across 9 targets (10k → 10M) with card drops and cosmetic rewards at each threshold
  • Implemented a full XP/levelling system with essence-based in-game economy — shop packs priced from 200 to 100,000 essence across 5 tiers
  • Game Design & Product

  • Designed the full game loop solo — collection, progression, daily rituals, economy, trading and end-game forging systems
  • Designed The Crucible (end-game legendary forging), The Fusion (seasonal one-of-one card), and a hidden easter egg system with server-side altar combos never publicly announced
  • Wrote lore for every card — 187 entries spanning Filipino, Japanese, Norse, Egyptian, Aztec, Slavic, Celtic, West African, Middle Eastern and dozens more mythologies and phenomena
  • Planned and managed the full product roadmap solo — features, card batches, release sequencing, engagement loops and launch strategy
  • Running a live social media presence (@infinitecollectibles.io on Instagram) with original content driving organic growth ahead of launch
  • Tooling & Process

  • Built internal Python tooling to automate card tracking and culture/type distribution analysis across the full card catalogue
  • Built the Variant Builder dev tool for designing card effects without code — saving hours per card batch
  • Maintained a structured card tracker (xlsx) with rarity, culture, type and gap analysis driving all expansion decisions
  • Managed the full CI/CD pipeline — Railway for API, Netlify for frontend, GitHub for version control — with zero-downtime deploys
  • Tech Stack
    React · TypeScript · Vite · Tailwind CSS · Framer Motion · Node.js · Express · PostgreSQL · Drizzle ORM · Clerk Auth · Railway · Netlify · Canvas API · GitHub · Python


    InfiniteCollectibles.io — Digital Collectibles Platform

    Role: Solo Developer · UI/UX Designer · Product Designer

    Overview
    InfiniteCollectibles.io is the live marketing and landing platform for the Infinite Collectibles card game — designed to drive signups, communicate the product vision and serve as the public face of the brand ahead of and during launch.

    What I Built

  • Designed and built the complete brand identity and design system for the Infinite Collectibles universe
  • Built the marketing site with animated hero, feature highlights, pack reveal previews and signup conversion flow
  • Integrated authentication and account creation flow connecting directly to the game platform
  • Executed SEO and metadata strategy to build organic presence ahead of launch
  • Managed all product and brand decisions — tone of voice, visual identity and community positioning
  • Tech & Tools
    React, TypeScript, Vite, Tailwind CSS, Clerk Auth, Netlify, SEO, UI/UX Design, Brand Design


    Insightfuls — All-in-One Business Reporting & Forecasting Platform

    Role: Solo Developer · UI/UX Designer · Product Designer

    Overview
    Insightfuls is a SaaS business intelligence platform that combines reporting, KPI tracking, cash flow forecasting and financial analysis into a single refreshingly clean management solution. Designed and built entirely from scratch as a solo developer — from initial concept and brand identity through to a fully deployed, subscription-based product.

    What I Built

  • Designed the complete UI from scratch — brand identity, colour system, typography, component library and all page layouts
  • Built a multi-page marketing website with animated sections, testimonials, pricing tiers and a contact flow optimised for conversion
  • Developed the full SaaS application backend including user authentication, role-based access, and a REST API powering the dashboard
  • Implemented subscription-based payment processing — tiered plans, billing management and upgrade flows
  • Built interactive KPI dashboards, cash flow forecasting views and automated reporting features within the product
  • Integrated a shopping cart / package selection flow for onboarding new clients
  • Executed full technical SEO — structured data, meta optimisation, page speed, sitemap and semantic HTML throughout
  • Managed end-to-end product decisions: feature prioritisation, user flows, onboarding UX and continuous iteration based on user feedback
  • Tech & Tools
    Frontend, Backend, REST API, Payment Processing, Authentication, Database, SEO, UI/UX Design, Brand Design


    MATA — Transparency & Evidence Platform for Infrastructure Monitoring

    Role: Solo Developer · UI/UX Designer · Product Designer

    Overview
    MATA is an independent project verification and monitoring platform built for government agencies and private firms. It provides transparent, evidence-based tracking of infrastructure and construction projects — helping organisations save time while ensuring accountability at every stage of execution.

    What I Built

  • Designed the full brand identity, visual language and UI system — clean, data-forward aesthetic suited to government and enterprise clients
  • Built the complete marketing site with multi-level navigation, technology section, team pages and insights blog
  • Developed an interactive geospatial mapping interface allowing clients to view and monitor project locations across the UK
  • Built the backend platform enabling independent evidence upload, project milestone tracking and verification workflows
  • Implemented secure stakeholder portals with role-based access for project owners, verifiers and client teams
  • Designed the information architecture and user flows for the evidence submission and review process
  • Executed technical SEO strategy targeting government procurement and infrastructure monitoring search terms
  • Managed all product decisions solo — from initial problem framing through to feature scope, design system and deployment
  • Tech & Tools
    Frontend, Backend, REST API, Mapping/Geospatial, Authentication, Database, SEO, UI/UX Design, Brand Design


    TopDrone — Drone Roof & Property Inspection Services

    Role: Solo Developer · UI/UX Designer · SEO Strategist

    Overview
    TopDrone is a commercial drone inspection and aerial documentation service targeting homeowners, insurers, landlords and property professionals across the UK. I designed and built the full website and booking/quote system, helping the business win clients including Lambeth Council, Croydon Council, Croydon Housing, Crystal Palace Park Trust and Better.

    What I Built

  • Designed the complete brand identity, logo, colour system and all UI — bold, trust-led aesthetic targeting property and insurance professionals
  • Built the full marketing website with service breakdowns, pricing structure, image gallery and social proof sections
  • Implemented a Free Quote request flow — structured lead capture form feeding into the booking pipeline
  • Integrated payment processing for booking deposits and service packages
  • Built the Insights / blog section for SEO content and industry authority
  • Executed a targeted local SEO strategy — the site ranks for relevant property inspection and drone survey terms across London boroughs
  • Created and embedded a sample PDF inspection report to demonstrate service quality and drive conversions
  • Set up and managed a scrolling client logo showcase highlighting council and housing association partnerships
  • Handled all copywriting — service descriptions, pricing justification, trust signals and FAQs
  • Tech & Tools
    Frontend, Backend, Payment Processing, SEO, Lead Generation, UI/UX Design, Brand Design, Copywriting


    Data Analysis

    Alongside my engineering and design work, I have a strong background in data analysis and business intelligence — using Python, SQL, Tableau and Power BI to explore datasets, build dashboards and extract actionable insights. The projects below range from exploratory data analysis and geospatial crime mapping to healthcare cost modelling and sales forecasting.

    Tools & Skills: Python · Pandas · Seaborn · Matplotlib · Streamlit · SQL · Excel · Tableau · Power BI · Statistical Analysis · Dashboard Design · Data Storytelling · EDA · Forecasting


    Current Project

    Tableau - UK Street Crime 2024 | Analysis - FINAL

    Tools Used for this Project
    Python and Tableau


    Etsy Shop | Full Year Calendar Heatmap - Sales & Forecast Summary

    Purpose
    To analyze and visualize sales performance of an Etsy shop over the course of a year, providing insights into sales trends, monthly performance, and geographical distribution of orders.

    Objectives

  • Daily Sales Heatmap: Create a full-year calendar heatmap to visualize daily sales data, highlighting patterns and anomalies in sales activity.
  • Monthly Sales Analysis: Compare actual monthly sales figures against estimates to assess forecasting accuracy and identify trends.
  • Geospatial Analysis: Map order locations to understand regional sales distribution and identify potential market opportunities.
  • This project aims to offer a comprehensive overview of sales performance and help in making data-driven decisions for optimizing sales strategies and improving forecasting accuracy.

    Tools Used for this Project
    Tableau


    Cardiac Triage Questionnaire App (app)

    Purpose and Objectives
    The Cardiac Triage Questionnaire app is designed to streamline the patient intake process by assessing and recording the severity of cardiac symptoms upon arrival or registration. Using a simple Python-based interface, this tool provides a quick and efficient way to prioritize patient care based on their triage scores.

    The primary purpose of the app is to facilitate effective and timely triage decisions in a healthcare setting. By evaluating patient responses to a series of pre-defined questions, the app calculates a total score that indicates the urgency of the patient's condition.

    Scoring and Action

  • Total Score Greater Than 4: The app triggers a triage call to ensure immediate attention for potentially severe conditions.
  • Total Score Less Than 4: Patients with lower scores are directed to proceed with standard booking procedures, allowing healthcare providers to manage their workload effectively.
  • The app can be seamlessly embedded into an HTML website or integrated into existing applications, providing a user-friendly interface for healthcare professionals and enhancing patient management efficiency.

    Key Points:

  • Efficiency: Quickly assesses and records patient conditions to aid in prioritizing care.
  • Integration: Can be embedded into websites or other applications for easy access and use.
  • Scoring System: Provides actionable outcomes based on a calculated score, facilitating prompt and appropriate care responses.
  • Tools Used for this Project
    Python and Streamlit


    Latest Project

    Insights into Healthcare Costs | Identifying Key Drivers (Data Analysis)

    See Full Overview

    Purpose and Objectives
    To understand the factors that influence medical insurance costs and to develop predictive model for estimating healthcare expenditures. My analysis is focused on both the descriptive and diagnostic aspects, leveraging individual data to build models that can forecast or estimate future healthcare expenditures.

    Scope

  • Loading and preprocessing the data
  • Conducting Exploratory Data Analysis (EDA)
  • Visualizations
  • Performing correlation analysis
  • Summarizing the findings
  • Deriving actionable insights to guide insurance companies and public health initiatives
  • Tools Used for this Project
    Python, Pandas, Seaborn, Matplotlib and PowerPoint


    Tableau - UK Police Force | Street Crime Dashboard | January - April 2024: Monitoring Trends and Hotspots (Dashboard)

    See Full Overview

    Scope

  • 330 UK Boroughs/Councils
  • 42 Territorial Police Force (excluding the Manchester Police - due to a change in IT systems)
  • Purpose and Objectives
    Monitoring trends and identifying hotspots in street crime in the UK

    Questions it should answer: What are the trends in street crime over the specified period? Where are the hotspots of street crime located?

    Decisions it should inform: Deployment of police resources, adjustment of crime prevention strategies, and allocation of investigative efforts.

    Tools Used for this Project
    Tableau, Excel, Power BI, and Python


    Power BI - UK Street Crimes | KPI Cards | January - May 2024


    Tableau - Metropolitan Police | Street Crime Data | January - April 2024


    Power BI - Metropolitan Police | Stop & Search | January - April 2024

    See Full Overview


    Power BI - Metropolitan Police | Street Crime | January - April 2024

    See Full Overview


    Just IT Assignments

    Power BI - Practical Task - Caffeine Form


    Power BI - Executive Summary Dashboard (Dark)


    Power BI - Executive Summary Dashboard (Light)


    Power BI - Sales Report Dashboard


    Power BI - Dashboard Exercise


    Tableau - The Wealth of Nations

    See Full Overview


    Tableau - Changes in the British Industry


    Tableau - Superstore Profit Dashboard


    Tableau

    Tableau - Resume

    Tableau - Report Turnaround Times - Imaging Department (finding breach)


    Tableau - Patient Satisfaction Survey Results - Imaging Department


    Tableau - Mandatory Training Compliance Dashboard

    See Full Analysis


    See my GitHub Repository



    Page template forked from evanca