Caleb Rotich, Developer in Nairobi, Nairobi County, Kenya
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Caleb Rotich

Verified Expert  in Engineering

Software Developer

Nairobi, Nairobi County, Kenya

Toptal member since February 28, 2022

Expertise
Front-endFull-stackSaaSDashboardBack-end DevelopersLLMJavaScriptReact.jsCSSBootstrapTypeScriptReduxHTML5
Bio

Caleb is a versatile full-stack software engineer known for delivering robust, user-focused web solutions. With a background spanning the education, eCommerce, and management sectors, he has helped scale applications to serve millions. His expertise spans web architecture, server-side and client-side development, and performance optimization. Caleb’s collaborative approach and strong communication skills make him an effective leader and team player in distributed, cross-functional environments.

Portfolio

Bahasha Tech
Next.js, NestJS, MongoDB, Redis, Grafana, Prometheus, Tailwind CSS, Node.js...
Chatsasa
Node.js, NestJS, React, Next.js, Antd, ChatGPT, Artificial Intelligence (AI)...
SMSLeopard
JavaScript, Node.js, A/B Testing, Jest, Cypress, Unit Testing, Flow, i18n...

Experience

  • JavaScript - 8 years
  • CSS - 7 years
  • React - 7 years
  • TypeScript - 6 years
  • Redux - 6 years
  • Next.js - 5 years
  • Tailwind CSS - 3 years
  • Material UI - 3 years

Availability

Full-time

Preferred Environment

MacOS, Linux, Slack, GitHub, Visual Studio Code (VS Code), Zoom, Firefox, Chrome, Google Hangouts, BlueJeans

The most amazing...

...project I've worked on is an eCommerce platform. The platform provides a great user experience and promotes an easy discovery of products and services.

Work Experience

Senior Full-stack Engineer

2024 - 2025
Bahasha Tech
  • Developed a NestJS back end with MongoDB and Redis to power bulk messaging via the Meta Cloud API, implementing a scheduling system that improved throughput by 50% and enhanced delivery success rates.
  • Built a wallet-based billing system with Stripe integration, transaction history tracking, and automated scheduled deductions while implementing robust admin controls for managing transactions and user accounts.
  • Designed and developed a responsive Next.js 15 interface using ShadCN and Tailwind CSS, delivering intuitive workflows for contact management, campaign tracking, and wallet management with real-time updates and clear error feedback.
  • Containerized the app with Docker and deployed it on Vultr with SSL certificates and reverse proxy setup while establishing a CI/CD pipeline using GitHub Actions to automate builds, image pushes, and deployments, reducing deployment time by 70%.
  • Implemented JWT-based authentication with RBAC, request rate limiting, and input sanitization to enhance security while optimizing database queries and introducing Redis caching to reduce processing delays by 40%.
Technologies: Next.js, NestJS, MongoDB, Redis, Grafana, Prometheus, Tailwind CSS, Node.js, Express.js, NGINX, Vultr, VPS, Vercel, Docker, Docker Hub, Docker Swarm, Shadcn, Passport.js, Windsurf, Cursor AI, AI Agents, Large Language Models (LLMs), React Components, API Integration, OpenAI, OpenAI API, ChatGPT, OpenAI Assistants API

Full-stack Developer

2023 - 2024
Chatsasa
  • Developed an application that integrates artificial intelligence with human supervision to provide efficient and accurate customer support.
  • Improved the application's performance using Next.js for server rendering.
  • Built a performant server with Node.js to handle AI service.
Technologies: Node.js, NestJS, React, Next.js, Antd, ChatGPT, Artificial Intelligence (AI), Dashboards, CSS3, Less, Figma, Full-stack Development, Back-end, Social Networks, Social Networks Development, Full-stack, Windsurf, Cursor AI, AI Agents, Large Language Models (LLMs), React Components, API Integration, MongoDB

Senior Full-stack Developer

2023 - 2024
SMSLeopard
  • Integrated two-factor authentication with a security key to enhance the security and user experience of the web application.
  • Implemented Sentry and Google Analytics to track and monitor JavaScript errors, performance issues, and user behavior on the web application.
  • Developed and deployed bulk airtime and data purchase features, increasing customer satisfaction and revenue.
Technologies: JavaScript, Node.js, A/B Testing, Jest, Cypress, Unit Testing, Flow, i18n, Internationalization, Security, UI Testing, Sentry, Google Analytics, Google Analytics 4, Front-end Architecture, Front-end Design, Playwright, WCAG 2, APIs, Responsive UI, Babel, ESLint, Express.js, Progressive Web Applications (PWAs), MERN Stack, Design, Microfrontends, Cross-browser Compatibility, Responsive Web Design (RWD), Webpack, Version Control, Test Automation, JSON Schema, Charting, CSS3, Less, Figma, Full-stack Development, Back-end, Full-stack, Windsurf, Cursor AI, AI Agents, Large Language Models (LLMs), React Components, API Integration

Senior Front-end Developer

2022 - 2023
Marmalade Labs, Inc
  • Migrated the application across a major version, Next.js 12 to Next.js 13.
  • Improved the app performance via the Core Web Vitals by reducing the client-side JavaScript.
  • Oversaw the launch of the three major application versions, which introduced critical user-facing features.
Technologies: React, Apollo, Next.js, TypeScript, Tailwind CSS, GraphQL, Server-side Rendering (SSR), Single Sign-on (SSO), Google Sign-in, Slack, JavaScript, Storybook, OpenAI, Web Usability, Search Engine Optimization (SEO), Vercel, Hygraph (GraphCMS), Google Analytics, UI Development, Monorepos, Axios, Front-end Architecture, Front-end Design, React Query, APIs, React Server Components, Responsive UI, ESLint, Progressive Web Applications (PWAs), Design, Cross-browser Compatibility, Responsive Web Design (RWD), Webpack, Version Control, Test Automation, JSON Schema, NextAuth.js, CSS3, Figma, Tailwind UI, Cursor AI, AI Agents, Large Language Models (LLMs), React Components, API Integration

Senior Front-end Developer

2022 - 2022
Apaleo
  • Migrated web applications from legacy WordPress applications to performant React single-page applications.
  • Improved web vitals for the web applications, leading to highly optimized and performant applications.
  • Helped rebrand web applications by transforming designs and wireframes into high-quality modular code.
Technologies: React, Next.js, TypeScript, Tailwind CSS, Contentful, HTML, HTML5, Algorithms, JSX, NPM, i18n, Localization, Amazon Web Services (AWS), Web Development, Content Management Systems (CMS), Responsive Web Apps, Serverless, Front-end, Scrum, Microservices, User Experience (UX), User Interface (UI), Test-driven Development (TDD), Bitbucket, Front-end Development, SaaS, Slack, JavaScript, Web Usability, Search Engine Optimization (SEO), UI Development, Axios, Front-end Architecture, Front-end Design, APIs, Responsive UI, Babel, ESLint, MERN Stack, Design, Cross-browser Compatibility, Responsive Web Design (RWD), Webpack, Version Control, Test Automation, JSON Schema, Headless CMS, CSS3, Tailwind UI, React Components, API Integration

Senior Software Developer

2019 - 2022
Ideas Come To Life | ICTLife
  • Developed an eCommerce application that facilitates easy trades between merchants and customers.
  • Built and guided a team in developing a financial application that analyzes transactions and provides beautiful transactional statements. The application gained over 1,000 active users in one week.
  • Created an in-house messaging application to be integrated into the other company's products. The application facilitates quick communication between users without the need for third-party integrations.
  • Led front-end developer teams in ensuring efficient communication, collaboration, and quick delivery of tasks.
  • Helped product owners and managers in continuous brainstorming of product implementation ideas.
  • Updated and improved legacy applications to ensure optimal performance and security against common client-side attacks.
Technologies: JavaScript, React, Next.js, Node.js, Redux, Material UI, HTML, Sass, TypeScript, MacOS, Software Engineering, Data Structures, CSS, GitHub, HTML5, Algorithms, React Redux, Amazon Web Services (AWS), Web Development, Responsive Web Apps, OAuth, JSON Web Tokens (JWT), REST APIs, Front-end, Scrum, Microservices, User Experience (UX), User Interface (UI), Test-driven Development (TDD), React Router, Bitbucket, Front-end Development, SaaS, Server-side Rendering (SSR), Google Sign-in, Single Sign-on (SSO), Tailwind CSS, Slack, Material Design, Web Usability, Search Engine Optimization (SEO), WordPress, Vercel, Google Analytics, Google Cloud, Firebase, Docker, Stripe API, UI Development, Monorepos, Axios, Front-end Architecture, React Query, APIs, Responsive UI, Babel, ESLint, Express.js, Progressive Web Applications (PWAs), Ant Design, Responsive Web Design (RWD), Webpack, Version Control, Test Automation, JSON Schema, NextAuth.js, Charting, Dashboards, CSS3, React Components, API Integration

Front-end Developer

2019 - 2020
LifeStores Pharmacy
  • Developed an app that manages the medical inventory of the pharmacy.
  • Created a scalable and thoroughly tested app with front-end testing tools.
  • Worked with the back-end team and designers to provide rich, user-driven interfaces.
Technologies: React, JavaScript, TypeScript, CSS, GraphQL, Redux, Material UI, HTML, Software Engineering, Data Structures, GitHub, Web Development, Front-end, Scrum, User Experience (UX), User Interface (UI), React Router, Bitbucket, Front-end Development, SaaS, Slack, UI Development, Axios, Responsive UI, ESLint, Responsive Web Design (RWD), Version Control, CSS3, React Components, API Integration

Software Engineer

2018 - 2019
Freelance
  • Worked on in-house applications that streamlined the daily operations of the company.
  • Built an education system that managed examination processing for schools.
  • Guided junior developers and provided mentorship in their early developmental journey.
Technologies: Python, Django, React, HTML, Material UI, Redux, JavaScript, Software Engineering, Data Structures, CSS, GitHub, Front-end, REST APIs, Jira, Scrum, User Experience (UX), User Interface (UI), React Router, Bitbucket, Front-end Development, SaaS, Slack, PostgreSQL, Stripe, Search Engine Optimization (SEO), CI/CD Pipelines, UI Development, NestJS, Axios, React Query, Responsive UI, ESLint, MERN Stack, Responsive Web Design (RWD), Version Control, Bootstrap, CSS3, Less, Vue, Tailwind UI, API Integration

Front-end Developer

2017 - 2018
Faiyol Systems Limited
  • Developed an examination system application with C# and JavaScript.
  • Wrote well-designed, testable, and efficient code using the best software development practices, raising the efficiency and speed of the company's application.
  • Managed the complete development process of an application from inception to deployment.
Technologies: .NET Core, C#, JavaScript, HTML, Software Engineering, Data Structures, CSS, GitHub, Web Development, Front-end, User Experience (UX), User Interface (UI), Front-end Development, Slack, PostgreSQL, UI Development, Responsive UI, Responsive Web Design (RWD), Version Control, Bootstrap, CSS3, Vue, API Integration

Experience

Marketplace App

https://www.africasasa.com
A JavaScript application that provides a smooth marketplace experience. The application helps users discover trusted local businesses to interact with and find services, food, activities to do, and places to stay closer to them.

AI-powered eCommerce Application

A React and Python-based application that lets users create a profile and then uses AI to show real makers, inventors, designers, artisans, and family-owned businesses who value what the user values.

Whether the user is all about sustainability, looking for products built to last, or wants to treat themselves to something special, the application is designed to help them explore products made by brands that care about their craft. The app is like a search engine laser-focused on small and independent brands online.

Application Store

https://store.apaleo.com/
A Next.js application that categorizes applications in a hospitality platform. I was in charge of building new interfaces and ensuring the application was highly performant. I optimized the application by ensuring the site was static through pre-generating pages from dynamic data.

Web App Migration and Rebranding

https://apaleo.com/
A company website built with React and NextJS. This project featured a fully customizable website generated by a database and statically rendered with Next.js. I took part in planning and developing data models and components for the app.

eCommerce Application for Merchants

https://merchant.africasasa.com
A React-based application that enables merchants to create business profiles and sell products in the marketplace.

I worked on the user interface and ensured a smooth user experience between different application sections. I got to work with modern web development tools like Next.js while ensuring high application performance.

School Examination Management System

https://github.com/calebrotich/ExaminationSystem
A .NET Core-based application for processing examinations in local universities.

I worked on the JavaScript and CSS front end as well as the .NET back end. The application integrated third-party integrations to output rich results processed by the system.

Freelancing Hub

https://github.com/calebrotich/Freelancers-hub
A PHP-based application that connects freelancers and clients.

This application contains algorithms that enable efficient matching of job seekers with the available job opportunities.
I won developer contests with the implementation of this application.

Command Line Interface Chat

https://github.com/calebrotich/cli-chat
A Python command-line interface chat system meant to be added as integration to web applications that require chat services.

I led a team in building the application using Python-provided command-line tools like Click, Docopt, and Fire.

Bulk SMS App

https://smsleopard.com/
A React-based application that enables users to send and manage promotional messages in bulk. I joined as a full-stack developer focusing on the front-end part of the application. I liaised with the back-end developer to bring in new features and improve the application's performance, security, and stability.

ChatSasa | AI-powered Customer Support

https://www.chatsasa.com
ChatSasa combines AI technology with human oversight to provide prompt, accurate, personalized customer support across different channels and languages. The integrated communication channels include WhatsApp, SMS, and chat widgets.

Messaging App for Meta API with Open AI

http://www.bahasha.app
A Node.js-based app for managing bulk messaging via the Meta Cloud API.

The app enables users to send personalized messages, schedule campaigns, and easily track delivery statuses. Built with NestJS and MongoDB, the platform features a robust billing system with wallet management, Stripe integration, and automated deductions. The Next.js 15 front end offers an intuitive interface for contact management, campaign tracking, and payment monitoring. Deployed on VPS using Docker containers, the app leverages Redis caching, optimized database queries, and a CI/CD pipeline for seamless updates, ensuring high performance, security, and scalability.

Education

2015 - 2018

Bachelor's Degree in Information Technology

Dedan Kimathi University Of Technology - Nyeri, Kenya

Certifications

DECEMBER 2020 - PRESENT

Associate Cloud Engineer, Google Africa Developer Scholarship

Google

SEPTEMBER 2018 - PRESENT

Mobile Web Specialist, Freelance Agency Learning Community

Freelance Agency

Skills

Libraries/APIs

React, Node.js, React Redux, REST APIs, React Router, Stripe API, React Query, RxJS, Stripe, Playwright, Vue, Antd, Passport.js, OpenAI API, OpenAI Assistants API

Tools

GitHub, JSX, NPM, JavaScript Testing, Jira, Bitbucket, Babel, Webpack, JSON Schema, Shadcn, Figma, Prisma, Hygraph (GraphCMS), Google Analytics, Slack, Zoom, Google Hangouts, Flow, Sentry, ChatGPT, Grafana, NGINX, Vultr, Docker Hub, Docker Swarm, Mongoose

Languages

JavaScript, Sass, CSS, TypeScript, GraphQL, HTML, HTML5, CSS3, Less, Python, C#, C++, Visual Basic, Java, PHP

Frameworks

Next.js, Redux, Material UI, Tailwind CSS, JSON Web Tokens (JWT), Express.js, Ant Design, Bootstrap, Django, Jest, Cypress, NestJS, Chrome, .NET Core

Paradigms

Software Testing, Testing, Scrum, Search Engine Optimization (SEO), Microfrontends, Responsive Web Design (RWD), Test Automation, Design Patterns, Automated Testing, Microservices, Test-driven Development (TDD), DevOps, Unit Testing

Platforms

MacOS, Linux, Contentful, Vercel, Amazon Web Services (AWS), WordPress, Firebase, Google Cloud Platform (GCP), Visual Studio Code (VS Code), Firefox, Docker

Storage

MongoDB, PostgreSQL, Google Cloud, Redis

Other

Software Engineering, Data Structures, i18n, Localization, Web Development, Content Management Systems (CMS), Full-stack, Responsive Web Apps, UI Testing, Front-end, User Experience (UX), User Interface (UI), Front-end Development, SaaS, Material Design, Web Usability, UI Development, Monorepos, Axios, Front-end Architecture, Front-end Design, APIs, React Server Components, Responsive UI, ESLint, Progressive Web Applications (PWAs), Cross-browser Compatibility, Version Control, Enzyme, NextAuth.js, Technical Leadership, Headless CMS, Charting, Dashboards, Tailwind UI, Full-stack Development, Back-end, Social Networks, Social Networks Development, Windsurf, Cursor AI, AI Agents, Large Language Models (LLMs), React Components, API Integration, Algorithms, Automated UI Testing, OAuth, Storybook, OpenAI, CI/CD Pipelines, WCAG 2, MERN Stack, Design, Artificial Intelligence (AI), BlueJeans, MVVC, Serverless, Apollo, Server-side Rendering (SSR), Single Sign-on (SSO), Google Sign-in, Radix UI, A/B Testing, Internationalization, Security, Google Analytics 4, Prometheus, VPS

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