Olusegun Banji
Fullstack Developer (FastAPI • React.js • Node.js • NestJS • NextJS • Django • Typescript)
About
Hello, I'm Olusegun Banji
COSPIRE leverages my expertise in ReactJS, NextJS, NestJS, Typescript, Django, NodeJS, and Firebase to develop mission-critical features, including a multi-step booking form that contributes to the company's revenue streams. My contributions include managing backend integrations, implementing secure routing, and optimizing search functionalities.
A Bachelor's degree in Computer Science and Economics from Obafemi Awolowo University underpins my technical foundation. Currently pursuing a Master's degree at Quantic School of Business and Technology, I specialize in creating scalable web solutions and conversational AI systems.
Services
Web Development
Building robust and scalable web applications with full-stack backends and slick frontends
API & Backend Integration
Crafting secure and maintainable APIs, handling authentication, databases, and business logic
PWA & UX Enhancement
Designing Progressive Web Apps with smooth interactivity and offline readiness
Skills
Experience
Full Stack Engineer
Cliniec Health Solutions
• Converted the Cliniec product into a pnpm/Turborepo monorepo of seven Next.js apps and shared packages (UI kit, typed API client, geo data, config)
• Built the Pharmacy, Lab and Hospital portals from Figma designs, including dashboards, appointments, results, messaging and reports, and wired the Hospital app to the hospital API
• Redesigned the public marketing site and built its portal picker for each vertical
• Set up Vercel deployments and a GitHub Actions workflow that mirrors main to a deploy repository
• Addressed code-review findings, including a timezone bug, swallowed errors and CI coverage
Full Stack Research Engineer (Backend focused)
MangoZestLab
• Researched and built backend and AI infrastructure for a Virtual Call Center, including OpenAPI-documented REST APIs and conversational AI features
• Designed the system architecture for a proposed self-hosted AI engine and acted as the bridge between the system under active development and the proposed engine
• Worked on Andromeda, a hospitality and travel platform built as a Turborepo/pnpm monorepo of six Next.js portals sharing one design system and a typed NestJS, Prisma and PostgreSQL API
• Published OpenAPI/Swagger documentation for the Virtual Call Center and Andromeda backends, and implemented mandatory TOTP two-factor sign-in for the Andromeda admin console
• Collaborated with cross-functional teams to integrate new technologies into existing services
Full Stack Engineer
Cospire (COSPIRE)
• Re-architected backend routing layer with Express.js, reducing API latency to sub-200ms
• Integrated 7+ external APIs (Firebase, Brevo, Google Maps, OpenStreetMap) to enhance platform services
• Led the development of a 5-step booking flow, boosting completion rate by 50%
• Optimized and secured SSO workflows with OAuth, cutting login errors by 60%
• Contributed to MVP2, helping secure 10+ early adopters and 3+ coworking partnerships
Key Achievements:
• Increased platform revenue by 20% through improved booking flow
• Reduced third-party request failures by 30% with resilient integrations
• Recognized by leadership for driving user adoption and platform growth
Software Engineer (Volunteer)
Indigitous
• Spearheaded development of a chatbot platform and real-time chat interface used by 500+ global users
• Integrated OAuth providers (Google and Facebook) to streamline user onboarding
• Built server-side rendered pages, improving SEO and page performance
• Designed and maintained a scalable social-media-like data model
Key Achievements:
• Reduced login drop-off by 35% with improved OAuth flows
• Increased page load performance by 45% and SEO ranking by 30%
• Co-led a 6-person dev team, achieving Top 8 placement in a global hackathon across 50+ cities
• Supported 1,000+ monthly social interactions through backend optimizations
AI/ML Engineer & Fullstack Developer
CISRG
• Built and deployed a GPT-2-based chatbot API handling 1,000+ monthly conversations across Messenger and Telegram
• Designed and implemented 10+ Flask RESTful endpoints with OAuth 2.0 authentication
• Fine-tuned LLM prompts to improve chatbot accuracy and retention
• Collaborated with a research team of 5+ on AI/ML projects
Key Achievements:
• Improved chatbot accuracy by ~40%, reducing user confusion
• Increased backend scalability and security through API design
• Co-authored 4 peer-reviewed publications, all scoring above 65% in external evaluations
Projects
Cliniec Health
A centralized healthcare technology platform for pharmacies, laboratories and hospitals, built as a pnpm and Turborepo monorepo of seven Next.js apps that share one design system and a typed API client.
Marketing Site
Public site with a portal picker for each vertical
Pharmacy Portal
Pharmacy and stores dashboard
Lab Portal
Labs and diagnostics: appointments, results, messages and directory
Hospital Portal
Hospitals and emergencies portal with departments and reports
In Progress
Specialist, patient and admin apps
Shared Packages
UI kit, typed API client, geo data and config
The sites above are live. The source is a private company repository, so get in touch if you would like a walkthrough.
Andromeda
A curated Nigerian hospitality and travel platform, built as a Turborepo monorepo: six Next.js apps for customers, members, hosts, businesses, partners and internal staff, all sharing one design system and a typed NestJS API.
Storefront
Customer-facing discovery and booking
Account
Signed-in member area
Host
Vendor portal for bookings and payouts
Business
Corporate accounts portal
Partners
Partner portal
Admin
Staff console with mandatory two-factor auth
API
NestJS service with Prisma, PostgreSQL and OpenAPI docs
Shared packages
UI kit, auth, data layer, types and config
Source code, live demos and test access are shared on request
This project is deployed and working, but the repository and demo access are kept private. Reach out and I'll share the links and a walkthrough.
vcc-uat-backend-dev
Virtual Call Center API — UAT/staging with OpenAPI docs and conversational AI features
OpenAPI, Conversational AI, REST API
andromedadev-backend
API documentation for Andromeda platform backend (developer docs)
API, OpenAPI/Swagger
poll-systems-backend
A Django backend for election polls
Django, PostgreSQL, Docker, REST API
Scarce2plenty
A crowd funding for agricultural goods sales app
React.js, Next.js, Firebase, TailwindCSS
Light Within Her
An blog website for healing, therapy and spiritual growth
Next.js, TailwindCSS, Sanity CMS
Apologist Chatbot Project
An AI-powered apologetics chatbot SAS
AI APIs (OpenAI), Next.js, Firebase/Auth
Indigitous Search Engine
A Non-copyrighted Search Application
Next.js, TailwindCSS, Custom APIs
Koinonia Divine Initiative Website
An official website for an international Christian NGO
React.js, Next.js, TailwindCSS
Blogging CRUD API Tutorial
A Blog CRUD Application
NestJS, TypeScript, REST API
SpaceX
A customized SpaceX landing page from their API
React, SpaceX API, Responsive Design
Tree of wally
A social media popularity monitization API
Node.js, Express, API Development
Medium Clone
A clone of medium.com
Next.js, Sanity CMS, TailwindCSS
Cospire
A B2B Space listing and booking startup
React.js, Node.js, Firebase, Google Maps
WhatsApp Web Clone
A clone of WhatsApp web
React, Firebase, Real-time Database
Growthbot PWA
Christian Discipleship Chatbot and Discipler connect App
React, PWA, Chatbot logic
Case Studies
Virtual Call Center — UAT / Conversational AI
Problem:
Businesses needed scalable, multilingual customer support with intelligent routing and analytics.
Solution:
Built a Virtual Call Center API with OpenAPI docs, conversational AI, call transcription, and omnichannel support.
Tech Stack:
OpenAPI, REST, Conversational AI, Transcription
Impact:
Enabled automated handling of inbound/outbound interactions and improved routing efficiency.
Andromeda Backend — API Docs & JWT Auth
Problem:
Developers needed clear, secure backend APIs with authentication and health checks.
Solution:
Provided OpenAPI documentation for the Andromeda backend with JWT-based auth and comprehensive endpoint definitions.
Tech Stack:
OpenAPI, JWT Auth, REST API, Health Endpoints
Impact:
Improved developer onboarding and faster integration using documented endpoints and auth flows.
Scarce2plenty — Agricultural Crowdfunding Platform
Problem:
Farmers lacked direct channels to market agricultural goods, facing middlemen costs.
Solution:
Built a crowdfunding/marketplace app enabling direct farmer-to-buyer sales.
Tech Stack:
React.js, Next.js, Firebase, TailwindCSS
Impact:
Improved farmer visibility; early beta allowed smallholder farmers to test fundraising models.
Light Within Her — Blog for Healing & Therapy
Problem:
Many individuals lacked an accessible platform for therapy and spiritual growth resources.
Solution:
Developed a blog site with easy CMS management and responsive layouts.
Tech Stack:
Next.js, Sanity CMS, TailwindCSS
Impact:
Empowered writers to publish quickly; grew community readership within first months.
Poll-systems-backend — Election Polling System
Problem:
Election systems needed transparent, secure backend APIs.
Solution:
Built Django-based backend with endpoints for polls, votes, and authentication.
Tech Stack:
Django, Python, PostgreSQL, REST Framework
Impact:
Enabled demo polling app; Loom walkthrough used in presentations for civic tech.
Feed Posts
Building Scalable React Applications
Best practices for structuring large React applications with proper state management and component architecture.
NestJS vs Express: A Developer's Perspective
Comparing two popular Node.js frameworks and when to choose each for your next project.
Firebase vs Supabase: The Database Showdown
A comprehensive comparison of two popular Backend-as-a-Service platforms for modern web applications.
Hire Me
Ready to bring your ideas to life? Let's discuss your project and create something amazing together. I'm available for freelance contracts and full-time opportunities.
Let's Start a Conversation
Message me on WhatsApp for quick responses and project discussions
Availability
Available immediately
Response Time
Within 24 hours
Time Zone
WAT (UTC+1)
Contact
Let's Connect
Ready to bring your ideas to life? I'm available for new projects and collaborations. Let's discuss how we can work together to create something amazing.