Hi, I'm William Onsare
Frontend Engineer with 5+ years of experience building production SaaS products. Core contributor to ChatSasa; an AI-powered, human-supervised omni-channel customer support platform used by growing businesses.
About Me
I’m a Frontend Engineer with 5+ years of experience building and maintaining production-grade web applications using React, TypeScript, and modern frontend tooling. I specialize in translating product requirements and user needs into clean, scalable, and accessible interfaces that perform reliably in real-world environments.
Most of my recent work has been on ChatSasa, an AI-powered, human-supervised omni-channel customer support platform. There, I’ve contributed extensively to agent inbox workflows, dashboards, and AI-aided interaction surfaces. Working closely with backend engineers, product managers, and designers to ship features used daily by real teams. My focus is always on usability, performance, and long-term maintainability rather than flashy abstractions.
I’m particularly effective at bridging the gap between design intent and functional implementation. I value pragmatic component architecture, predictable state management, and clear UX flows that reduce cognitive load for users. Beyond code, I’m known for strong collaboration, ownership, and the ability to execute consistently under tight deadlines.
I’m currently open to mid-level to senior frontend, UI Engineer, or React/TypeScript-focused roles, and I adapt quickly to new tools and workflows where they serve the product and team better.
Technical Expertise
React, TypeScript, Next.js, modern state management, and scalable UI architecture.
Collaborative Delivery
Strong cross-functional collaboration with product, design, and backend teams.
User-Focused Interfaces
Building intuitive, accessible, and performance-conscious user experiences.
AI Product Integration
Hands-on experience integrating AI-powered features into production SaaS products.
How I Work
Production-Ready React
Deliver production-ready React apps with focus on performance and accessible interfaces.
Design to Code
Turn design wireframes into reliable components and measurable UX improvements.
Outcome Focused
Collaborate closely with product & ops; I prioritize outcomes over vanity features.
Featured Projects
Production apps demonstrating frontend engineering and UX thinking
ChatSasa - Smart Inbox
AI-Powered Omni-Channel Customer Support Platform
Problem
Businesses struggle with fragmented customer messages across channels (WhatsApp, email, SMS, socials), slow response times, and no unified analytics to prioritise high-value tickets.
My Role
Lead frontend developer: designed and implemented the product UI, built responsive interactive components, integrated analytics visualisations, and delivered the smart-inbox flows used by support agents.
Tech Stack
Impact
- Consolidated multi-channel conversations into a single inbox, increasing agent throughput
- Reduced average response and resolution times through prioritised queues and task assignment
- Delivered dashboard analytics that inform daily ops and surface performance trends
User-friendly inbox, fast-loading analytics, frictionless CTAs for onboarding & trial conversions.
SMSLeopard Broadcast Platform
Communication / SaaS
Problem
Businesses needed a dependable way to run large-scale SMS & WhatsApp broadcast campaigns, and integrate messaging into existing systems without losing deliverability or developer ergonomics.
My Role
Frontend contributor working with a team of senior engineers - I implemented recent features, wired frontend components to APIs, improved developer-facing docs/examples, and assisted with QA and performance tuning.
Tech Stack
Impact
- Reduced campaign setup time through a streamlined broadcast composer and templates
- Enabled external integrations via developer APIs, making it easier for clients to automate messaging workflows
- Improved dashboard visibility and analytics so operations could monitor campaign health and troubleshoot faster
API integration hooks, dashboard analytics, testing, documentation, and release coordination.
M-Pesa Hash Decoder
Developer Tool / Payments Utility
Problem
Kenyan businesses and support teams needed a fast, reliable way to decode and verify M-Pesa/Paybill transaction hashes to troubleshoot payments and reconcile records.
My Role
Solo frontend implementation: designed UI, implemented API integration, added copy/paste-friendly workflows.
Tech Stack
Impact
- Reduced time-to-verify M-Pesa transactions from 20+ minutes to under 2 minutes
- Improved reconciliation accuracy for finance teams and reduced support ticket volume
- Adopted by small merchants for quick on-the-spot verification during customer disputes
Clear onboarding, clean UX for parsing data, copy/clipboard flow.
PodoaPlus
Marketplace - Beauty & Wellness Prototype
Problem
Local beauty professionals lacked a trustworthy, discoverable channel to attract clients and manage bookings efficiently.
My Role
Lead frontend / UX: designed landing and search-first discovery UI, implemented booking & provider signup flows, integrated reviews/testimonials and responsive layouts.
Tech Stack
Impact
- Lowered discovery friction — users find relevant pros via service + location search in one step
- Streamlined business onboarding and service listings for local professionals
- Improved conversion with clear pricing, social proof and an easy booking flow
Progressive enhancement, navigation persistence, mobile-optimized flow.
Skills & Expertise
Frontend Engineering
- React, TypeScript, Next.js
- Component architecture & reusable systems
- State management & data flow
- Performance optimization & web vitals
Product & UX Collaboration
- Translating product requirements into UI systems
- Iterative design with real users
- Accessibility & usability considerations
AI-Powered Systems
- OpenAI API integrations
- AI-aided workflows (human-in-the-loop)
- Message classification & response suggestions
Platforms & Integrations
- WhatsApp Business API
- Google RCS
- SMS gateways
- REST & GraphQL APIs
Education & Languages
Education
Bachelor's Degree in Applied Computer Science
Chuka University
2015 - 2019
Languages
Let's Connect
Open to opportunities, let's discuss how I can contribute to your team