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Isaac Ssemugenyi, Frontend Engineer

I build interfaces that stay fast, responsive and reliable as products scale.

I'm Isaac, a frontend engineer with 4+ years of experience building with React and TypeScript. I've shipped payment flows, operational dashboards and booking platforms, with a focus on the details users experience most: speed, reliability, clear errors and interfaces they can trust.

View the workRésumé
  • 4+years shipping frontend
  • 10projects delivered
  • 6industries
  • TStyped end to end

Technologies and practices

  • React
  • TypeScript
  • JavaScript (ES2023)
  • Redux Toolkit
  • RTK Query
  • React Router
  • TanStack Query
  • TanStack Router
  • TanStack Start
  • TanStack Table
  • TanStack Form
  • Tailwind CSS
  • CSS Modules
  • Styled Components
  • SASS
  • Design systems
  • Responsive layout
  • WCAG 2.2 AA
  • Core Web Vitals
  • Code splitting
  • Render optimisation
  • Bundle analysis
  • Image and font strategy
  • Caching
  • Test-driven development
  • Vitest & Jest
  • React Testing Library
  • Integration testing
  • End-to-end testing
  • Mocking & test doubles
  • Coverage as a signal, not a target
  • Google Analytics 4
  • Google Tag Manager
  • Google Search Console
  • Event & conversion tracking
  • Meta & canonical tags
  • Structured data (JSON-LD)
  • Open Graph & social cards
  • Sitemaps & robots.txt
  • Claude and OpenAI APIs
  • Streaming responses
  • Tool calling
  • Structured output
  • Prompt design
  • Retrieval augmented generation
  • Token and cost budgeting
  • Rate limits and error states
  • Table-based layout
  • Inline styles
  • Outlook and Gmail quirks
  • Plain text alternatives
  • Preheader text
  • Dark mode inboxes
  • Deliverability basics (SPF, DKIM)
  • Nodemailer and SMTP
  • Git & GitHub
  • GitHub Actions
  • CI/CD pipelines
  • Agile delivery
  • Cross-browser debugging
  • Code review
  • Mentoring & onboarding
  • Technical decisions
  • Scoping & estimation
  • Setting conventions
  • Documentation & handover

Selected work

Projects I've delivered

4+ years building for fintech, marketplaces and SaaS. Each case study covers the problem, what I built and what I learned from it.

  • mookh.com
    The Mookh homepage, showing event discovery search and category filters.
    Marketplace

    Mookh

    Creator commerce and event ticketing platform serving organisers across East Africa.

    • Next.js
    • React
    • TypeScript
    • Tailwind CSS
    • +1
  • cafe-jafn-4a82f.web.app
    The Cafe Jaf'n dashboard sign-in screen, in the cafe's brown and cream brand palette.
    Hospitality

    Cafe Jaf'n Dashboard

    Restaurant management dashboard for an independent cafe, built solo in React and Tailwind CSS on Firebase.

    • React
    • Vite
    • Tailwind CSS
    • Firebase
  • admin.mailgorillachimp.com
    The MailGorilla admin sign-in screen for the email dashboard.
    SaaS

    MailGorilla Admin

    Admin dashboard for an email sending and delivery tracking platform, built solo in React and Tailwind CSS.

    • React
    • Vite
    • Tailwind CSS
  • Marketplace

    Glam n Go Marketplace

    Multi-vendor marketplace for women’s and kids’ clothing. I built the merchant dashboard and the platform admin dashboard.

    • React
    • TypeScript
    • Tailwind CSS
    • Redux Toolkit Query
    • +1
  • jebapesa.com
    The Jeba Pesa homepage, introducing the cooperative fintech platform.
    Fintech

    Jeba Pesa

    Consumer fintech interface for payments and transfers, built with React and CSS Modules against a Redux Toolkit Query data layer.

    • React
    • JavaScript
    • Redux
    • Redux Toolkit Query
    • +1
  • davsafaris.com
    The Davsafaris homepage, showing the tour search bar over a Ugandan landscape hero.
    Travel

    Davsafaris Tours Platform

    Feature work and performance fixes on a tours and travel booking platform, delivered with a distributed team.

    • React
    • JavaScript
    • Axios
    • CSS Modules
    • +1
  • davsafaris
    The Dav Safaris fleet operations sign-in screen, split between branding and the login form.
    Logistics

    Davsafaris Fleet Management System

    Operations system that pulls vehicle tracking, driver and booking assignment, inspections, maintenance and client messaging into one place.

    • React
    • JavaScript
    • Axios
    • CSS Modules
    • +1
  • fleet-tracking.davsafaris.com
    The Dav Safaris client portal sign-in, which sends a secure email link instead of asking for a password.
    Logistics

    Davsafaris Client Portal

    Client-facing companion to the fleet system, giving travellers a direct line to the driver assigned to their trip.

    • React
    • JavaScript
    • Axios
    • CSS Modules
    • +1
  • dav-safaris-admin-portal.web.app
    The Dav Safaris admin portal sign-in, a dark card on a green patterned background.
    Travel

    Davsafaris Admin Portal

    Back office for the Davsafaris tours platform, where the tours, content and bookings the public site sells are actually managed.

    • React
    • Tailwind CSS
    • Firebase
  • dav-agent-dashboard.web.app
    The Dav Safaris agent portal sign-in, set over a savannah sunset with a frosted glass form.
    Travel

    Davsafaris Agent Dashboard

    Booking dashboard for travel agents selling group tours, covering tour listings, client bookings and full booking history.

    • React
    • Vite
    • Tailwind CSS
    • Firebase
See all work

Skills

Areas of expertise

Key areas where I bring practical experience, technical expertise and a track record of delivering production-ready solutions.

  • Core

    The technologies I work in most closely. I have delivered production work with them every year of my career.

    • React
    • TypeScript
    • JavaScript (ES2023)
    • Redux Toolkit
    • RTK Query
    • React Router
    • TanStack Query
    • TanStack Router
    • TanStack Start
    • TanStack Table
    • TanStack Form

  • Interface & styling

    Turning a design file into an interface that holds up everywhere it lands, across screen sizes, themes and however someone chooses to navigate it.

    • Tailwind CSS
    • CSS Modules
    • Styled Components
    • SASS
    • Design systems
    • Responsive layout
    • WCAG 2.2 AA

  • Performance

    Making pages fast on the phones and connections the audience really has, not just on a high end laptop.

    • Core Web Vitals
    • Code splitting
    • Render optimisation
    • Bundle analysis
    • Image and font strategy
    • Caching

  • Testing & quality

    Writing the failing test first. It keeps the code honest about how it will actually be used, and it makes later changes far less risky.

    • Test-driven development
    • Vitest & Jest
    • React Testing Library
    • Integration testing
    • End-to-end testing
    • Mocking & test doubles
    • Coverage as a signal, not a target

  • Analytics & SEO setup

    Wiring measurement and the search essentials into a build. I handle the technical setup, and leave campaigns and content strategy to the specialists.

    • Google Analytics 4
    • Google Tag Manager
    • Google Search Console
    • Event & conversion tracking
    • Meta & canonical tags
    • Structured data (JSON-LD)
    • Open Graph & social cards
    • Sitemaps & robots.txt

  • AI integration

    Building model features people can actually rely on. Streaming, tool calls, and sensible behaviour when a response is slow, wrong or unavailable.

    • Claude and OpenAI APIs
    • Streaming responses
    • Tool calling
    • Structured output
    • Prompt design
    • Retrieval augmented generation
    • Token and cost budgeting
    • Rate limits and error states

  • Email

    Designing and building transactional email that renders consistently across mail clients, from markup and layout through to deliverability.

    • Table-based layout
    • Inline styles
    • Outlook and Gmail quirks
    • Plain text alternatives
    • Preheader text
    • Dark mode inboxes
    • Deliverability basics (SPF, DKIM)
    • Nodemailer and SMTP

  • Engineering practice

    How the work travels from a branch to something live, reviewed and repeatable.

    • Git & GitHub
    • GitHub Actions
    • CI/CD pipelines
    • Agile delivery
    • Cross-browser debugging

  • Technical leadership

    The parts of the job that reach past my own tickets and help the people around me do their best work.

    • Code review
    • Mentoring & onboarding
    • Technical decisions
    • Scoping & estimation
    • Setting conventions
    • Documentation & handover

Experience

Professional experience

Hands-on experience across diverse products and teams, with a focus on end-to-end frontend development and technical ownership.

  1. Frontend Lead

    Current

    MookhRemoteRemoteFull-time

    Jan 2026 — Present

    • Lead frontend direction across the platform, setting the standards the rest of the work is reviewed against.
    • Own architecture decisions on state, component boundaries and performance budgets.
    • Review code and mentor engineers, focusing on the reasoning behind a change rather than only its output.
    • Next.js
    • React
    • TypeScript
    • Tailwind CSS
    • CI/CD pipelines

  2. Frontend Engineer

    MookhRemoteRemoteFull-time

    Sep 2024 — Dec 2025

    • Improve app speed and efficiency by optimising component rendering across the product surface.
    • Refactor existing code for readability and performance, splitting oversized components into composable units.
    • Identify and fix defects reported by users or caught during testing, tracing each to root cause.
    • Next.js
    • React
    • Tailwind CSS
    • Git workflows
    • CI/CD

  3. Frontend Engineer

    Jeba Jeba LimitedKampala, UgandaOn-siteContract

    Aug 2023 — Sep 2024

    • Implemented Figma designs in React at high fidelity for Jeba Pesa, a consumer fintech product.
    • Integrated API endpoints and handled data flows through Redux Toolkit Query, giving every screen consistent caching and error handling.
    • Optimised application performance and built responsive layouts with mobile treated as the primary case.
    • React
    • Redux
    • Redux Toolkit
    • JavaScript
    • CSS3
Full résumé

Also

I build WordPress sites too.

Custom child themes, Elementor Pro and WooCommerce for tour operators, law firms and non-profits. 7+ sites live, each one handed over to a client who runs it without me.

See the WordPress workStart a WordPress project

Have something worth building?

I'm open to frontend roles and freelance work. Tell me what you're working on and I'll tell you honestly whether I'm the right fit.

Start a projectDownload résumé