Zadat Olayinka, Developer in Liverpool, United Kingdom
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Zadat Olayinka

Verified Expert  in Engineering

Software Developer

Liverpool, United Kingdom
Toptal Member Since
August 16, 2022

Zadat is a diligent software engineer with over four years of professional experience building and deploying high-quality solutions for fintech, education, gaming, ticketing, and eCommerce. He has overseen projects from inception to client release and worked on hybrid mobile applications, API/microservices, SDKs/plugins, and web applications. Zadat understands the importance of quality code and excellent communication, which have been the core of his achievements over the years.


See Forge
Ionic, iOS, Android, TypeScript
DDM Health
JavaScript, PHP, Laravel, Vue, Redis, MongoDB, Full-stack, REST, APIs, Nuxt.js...
JavaScript, Express.js, Ruby, Go, Java, PHP, Python, Neo4j, MongoDB, React...




Preferred Environment

MacOS, Linux, Visual Studio Code (VS Code), Vim Text Editor, Slack

The most amazing...

...project I've built was a hybrid mobile application for managing pensions and investments used by over 100,000 clients to date.

Work Experience

Expert Ionic Developer

2023 - PRESENT
See Forge
  • Migrated Ionic from v5 to v7 and Capacitor from v4 to v5 to the latest version. Updated existing plugins and fixed broken changes in the codebase.
  • Investigated and fixed bugs with Microsoft Authenticator, allowing users with different Android versions to use the feature seamlessly.
  • Researched and advised on the technical decisions for future application releases aligned with business goals.
Technologies: Ionic, iOS, Android, TypeScript

Full-stack Engineer

2022 - 2023
DDM Health
  • Fixed existing bugs with features currently in production and reduced the request time of API requests by 60%.
  • Integrated the back and front end with Stripe, increasing sales by 25%.
  • Developed a care network management for new users and an integration with Slack, with over 400 users onboarded.
  • Designed a discount and reward system and integrated it with required departments and Stripe for a seamless process.
Technologies: JavaScript, PHP, Laravel, Vue, Redis, MongoDB, Full-stack, REST, APIs, Nuxt.js, REST APIs, Back-end, Back-end Development, System Design, API Architecture

Full-stack Engineer

2020 - 2021
  • Built an application monitoring system with 10,000+ clients, monitoring server time up, application error logs, error tracking with a stack trace, and root cause analysis.
  • Developed SDKs installable by third-party clients to interact with a server-side API in six languages.
  • Analyzed and classified data using Neo4j and graphical representation with D3.js.
  • Developed an AI email Chrome extension used in predicting email content.
  • Revamped a client's portfolio project using Gatsby.
  • Built a set of reusable website components in standardized styles to allow for reusability.
  • Improved test coverage to 75% for all existing features on microservices.
  • Developed an error tracking and application logging feature on the API and web app.
  • Worked on improving the API documentation to ease clarity for consumption by other developers.
  • Developed GitLab scripts for each microservice to manage the building, testing, and deployment to staging and production on GCP.
Technologies: JavaScript, Express.js, Ruby, Go, Java, PHP, Python, Neo4j, MongoDB, React, Redux, Mocha, Chai, JUnit, PHPUnit, Data Structures, Algorithms, Node.js, Amazon Web Services (AWS), Google Cloud Platform (GCP), Full-stack, Amazon Cognito, REST, APIs, Contentful, Next.js, REST APIs, Back-end, Back-end Development, Software Design, System Design, API Architecture

Full-stack Engineer

2019 - 2021
ARM Pensions
  • Developed a hybrid pension and investment management mobile application with 100,000+ users on Android and iOS platforms.
  • Developed a script for processing based64 files to binary files, which increased TAT by about 90% for processing application information on Microsoft Navision.
  • Integrated with Paystack to allow users to buy into different investments and bonds.
  • Built a Toolkit API used by staff to manage clients' data, monitor clients' activity, give insight into how to manage their pension, etc.
  • Developed multiple microservices to integrate with an external payment system for managing payroll.
  • Built a hybrid onboarding application used by sales agents in onboarding new clients to the pension system.
  • Converted mockups into the company website using Vue, Nuxt.js, and Tailwind CSS. Also, I built in new features and managed the web application.
  • Built an embassy request and statement request service.
  • Developed an employer portal used by employers to manage their staff's pension remittance, among others.
  • Developed a geolocator used by clients and staff agents to map the nearest clients trying to open a pension account with the agent in the area.
Technologies: JavaScript, PHP, Laravel, Lumen, Ionic, Cordova, Capacitor, Algorithms, Express.js, React, Mocha, Chai, PHPUnit, Node.js, SQL, Heroku, Next.js, Vue, Full-stack, REST, APIs, Contentful, Nuxt.js, REST APIs, Back-end, Back-end Development, TypeScript, Software Design, System Design, API Architecture, iOS, Android

Full-stack Developer

2019 - 2020
Touchcore Technologies
  • Built an internal VISA management application for an agency using Laravel and React.
  • Built a diagram ordering system for architectures using Laravel and React.
  • Integrated the existing application with Interswitch third-party APIs to process fee collection smoothly and seamlessly.
  • Developed API microservices for event and ticket management using Lumen.
  • Managed multiple site deployments to cPanel. Troubleshot in production.
Technologies: PHP, JavaScript, PHPUnit, Mocha, Chai, Full-stack, Tailwind CSS, Laravel, Lumen, CSS, React, cPanel, Web Hosting & Domain Setup, MySQL, Heroku, Apache, REST, APIs, Back-end, Back-end Development, TypeScript, Software Design, System Design, API Architecture

Software Engineer

2018 - 2019
Shopping Internet Services
  • Developed REST APIs using the TTD approach focused on correctness, authentication, authorization, scalability, and efficiency.
  • Worked in a team that delivered a field agent mobile application for bringing in new clients.
  • Increased test coverage on existing microservices by 40%.
  • Implemented features on the microservices built on the Spring Boot framework.
Technologies: Java, Hibernate, Angular, Ionic, OAuth 2, Spring Boot, JUnit, JavaScript, Mocha, CircleCI, Amazon Web Services (AWS), Google Cloud Platform (GCP), Heroku, cPanel, REST, APIs, Spring, API Architecture, iOS, Android

ARM Engage
ARM Engage is an Android and iOS application used for both investing and managing pensions. I built the UI from wireframes delivered to me and also built the APIs being used by the mobile application. I integrated the app with Firebase to manage crash analytics, push notifications, etc. It has over 100k users as of now and has a very impressive rating on both the Android and iOS stores.


Granula is a custom survey system where users can create custom questions with custom options, and users can also answer these surveys for a particular incentive.

• Users can create custom surveys.
• Users can create custom questions and options for each question.
• Users pay a particular fee to have access to the system.
• Respondents are vetted to be on the system.
• They are invited to respond to surveys that fit them.
• Respondent gets incentives in terms of airtime and cash for these surveys.
• Users get quality data that can be exported for further analysis.


WhotApp gives users the access to bet on the Whot playing card while they compete against one another

• Users can create an account with their social OAuth.
• Users can fund their accounts using paystack.
• Users can send invites to any other user to compete.
• Users play against each other in real time.
• Winner takes it all.

Ticketing App
A ticket management API used for creating and managing events, guests and invitations, and payment collection and refunds.

• Users are able to create accounts and create events.
• Different subscriptions decide what features users have access to.
• Events can be customized to users' perfection.
• Invitations can be sent out to the public.
• Tickets can be purchased and sales managed on behalf of the event organizer.
• Organizers have access to both funds and guests.


ChipTranz is a mobile application used by users to save money, it provides a seamless interaction, and it has processed over 5 million nairas over time. I integrated with an existing API for this project

• Users have access to creating saving plans.
• Users can integrate with payment systems like Paystack for reoccurring savings.
• Users can manage their savings.
• Users can make a withdrawal.
• Push notifications are also managed for users.


JavaScript, PHP, Go, Java, TypeScript, Ruby, Python, CSS, SQL, HTML, ECMAScript (ES6), HTML5


Express.js, Redux, JUnit, PHPUnit, Laravel, Lumen, Ionic, Tailwind CSS, Angular, OAuth 2, Next.js, Spring, Hadoop, Swagger, Hibernate, Spring Boot, Nuxt.js


React, Chai, Node.js, Vue, Stripe API, REST APIs


Mocha, Vim Text Editor, Slack, CircleCI, Apache, Firebase Analytics, Amazon Cognito


REST, Agile Software Development, API Architecture


MacOS, Linux, Contentful, Apache Pig, Visual Studio Code (VS Code), Amazon Web Services (AWS), Google Cloud Platform (GCP), Heroku, cPanel, Firebase, Docker, iOS, Android


Full-stack, APIs, Back-end, Back-end Development, Data Structures, Algorithms, Cordova, Capacitor, Software Design, System Design, Architecture, Machine Learning, Metaheuristics, Big Data, Web Hosting & Domain Setup, Hybrid Apps, ES6 Promises, Push Notifications


MongoDB, Redis, Neo4j, MySQL

2021 - 2022

Master's Degree in Computer Science

Liverpool Hope University - Liverpool, England

2014 - 2018

Bachelor's Degree in Computer Science

University of Ibadan - Ibadan, Nigeria