TheoCodes: Backend Engineering & Java Craftsmanship
I build robust, scalable backend systems with Java at the core. From REST APIs to microservices clean code, solid architecture, and systems that last.
Theophilus Thobejane@lab — zsh — 80×24
The Journey
A backend developer who believes great software starts with great fundamentals. Passionate about Java, clean architecture, and building systems that can scale. I thrive in the backend — where the real logic lives.
Java isn't just a language it's a discipline. From the JVM to Spring Boot microservices, I've invested deeply in understanding how Java works under the hood. Strong typing, OOP principles, and the rich ecosystem make it my weapon of choice for production-grade systems.
REST APIs, microservices, message queues, and database design are where I spend most of my time. I care about separation of concerns, SOLID principles, and writing code that other developers can actually understand and extend. Good backend code is invisible — it just works.
Every line of code is a solution to a problem. I approach backend engineering by deeply understanding the business domain first, then designing systems that reflect that domain clearly. Whether it's optimising a slow query or re-architecting a service — the goal is always clarity and reliability.
// My approach to software engineering
const philosophy = {
buildForScale: true,
automateEverything: true,
teachWhileLearning: true,
measureImpact: "94% RAG accuracy | 90.07% stock prediction | 70% pre-booking automation | 6 production projects",
currentStack: ["Python", "Node.js", "FastAPI", "PostgreSQL", "LLMs/RAG"]
};
Artifacts
Production systems built for real clients and real problems — AI pipelines, delivery platforms, verification tools, and data models. Not tutorials. Not clones.
2025
A Docker-composed microservices demo with service discovery, API gateway, and distributed tracing.
2024
A lightweight message queue implementation in pure Java, supporting publish/subscribe and point-to-point patterns with persistent delivery guarantees.
2024
A secure, multi-tenant REST API platform built with Spring Boot, featuring JWT authentication, role-based access control, and audit logging.
2023
A Java command-line tool for automated PostgreSQL backup, encryption, and upload to cloud storage.
2023
A minimalist ORM (Object-Relational Mapper) for Java, built to understand how Hibernate works beneath the abstractions.
Arsenal
Technologies I use to build production-ready systems. From databases to AI pipelines.
The Path
From student to teacher to builder. Every step taught me something about code, systems, and people.
Building backend systems and REST APIs for clients using Java, Spring Boot, and PostgreSQL. Delivering production-grade microservices, integrating third-party APIs, and consulting on backend architecture.
Building backend systems and REST APIs for clients using Java, Spring Boot, and PostgreSQL. Delivering production-grade microservices, integrating third-party APIs, and consulting on backend architecture.
Worked on a team maintaining and extending a large enterprise Spring Boot monolith. Key contributions: migrated SOAP services to REST, improved test coverage from 40% to 78%, and optimised critical database queries reducing p99 latency by 62%.
Worked on a team maintaining and extending a large enterprise Spring Boot monolith. Key contributions: migrated SOAP services to REST, improved test coverage from 40% to 78%, and optimised critical database queries reducing p99 latency by 62%.
Studied Computer Science with a focus on software engineering, algorithms, and systems programming. Final-year project: a distributed task scheduling system built in Java with a custom load balancing algorithm. Graduated with merit.
Studied Computer Science with a focus on software engineering, algorithms, and systems programming. Final-year project: a distributed task scheduling system built in Java with a custom load balancing algorithm. Graduated with merit.
Passed the Spring Professional certification exam (VMware Spring Professional 2024). Covers Spring core, Spring MVC, Spring Security, Spring Data, Spring Boot, and Spring AOP.
Passed the Spring Professional certification exam (VMware Spring Professional 2024). Covers Spring core, Spring MVC, Spring Security, Spring Data, Spring Boot, and Spring AOP.
Earned the AWS Cloud Practitioner certification, covering core AWS services, cloud concepts, pricing, security, and architectural best practices relevant to backend deployments.
Earned the AWS Cloud Practitioner certification, covering core AWS services, cloud concepts, pricing, security, and architectural best practices relevant to backend deployments.
Field Notes
Quick observations, experiments, and discoveries from the digital laboratory.
Building a layered security filter chain in Spring Security 6 — JWT validation, IP allowlisting, and request signing.
How I found and fixed a catastrophic N+1 query problem using Hibernate's SQL logging and query count assertions.
Experimenting with Java 21 virtual threads — massive throughput improvement for I/O-bound tasks with near-zero thread overhead.
Building a layered security filter chain in Spring Security 6 — JWT validation, IP allowlisting, and request signing.
Current Focus
What's currently on the workbench — active projects, experiments in progress, and things being built.
Exploring new Java 21 features: virtual threads, record patterns, sequenced collections.
Exploring new Java 21 features: virtual threads, record patterns, sequenced collections.
Building and personalising this portfolio site — dynamic content, admin dashboard, and chatbot integration.
Implementing Eureka-based service discovery and client-side load balancing in the mesh project.