Abstract. I'm Amal Babu, a full-stack software developer
and tech lead at Hybrid Interactive in Kochi, India. I build scalable
software that solves business problems, including ERP and CRM systems, for
clients in healthcare, construction, e‑commerce and influencer
marketing, and I add AI where it does useful work. Across all of it I put
structure first: clear module boundaries, dependencies that point one way,
and a data model that fits the domain. In my experience, that's what keeps
a system easy to change as it grows [1]. I've
led six client systems as technical lead. This page is a guide
to my writing and my work. My full work history, skills and education are
on the About page.
Keywords: software architecture, system design,
full-stack development, domain-driven design, FastAPI, Django, Next.js,
PostgreSQL, AI integration
Business software rarely gets hard because of one piece of code. It gets hard because of its size: many connected rules, relational data and requirements that keep changing. This article sets out the five principles I design by (separation of concerns, one dependency direction, modules by business capability, a frontend that mirrors the backend, and AI only where it does real work), the architecture they produce, and what that structure costs.
A deep dive into building maintainable and scalable software systems using a Modular Monolith architecture with FastAPI. Learn how proper project structure can save your codebase from tech debt.
I've been at Hybrid Interactive since May 2025, leading a small team. Table 1 lists the client systems I've led there, most recent first. The clients
are confidential, so each project is described rather than named. All of them are described on the Client projects page.
Table 1. Client projects, most recent first, with my
role on each.
Figure 1 shows the architecture these systems share, as set out in [1]. Frontends talk to one API layer. Behind it, the backend is a single
deployable divided into business modules, which share only core
infrastructure. Many of these backends start from our open-source template [2].
Figure 1.The architecture the systems in Table 1 share. Select a box to read what it is; the one marked with an arrow opens its code.
3Open source
Table 2 lists my two open-source tools: one for starting a backend and one for
deploying it. The design decisions behind each are on the Systems page, and my other code is at github.com/amal-babu-git.
Table 2. Open-source tools.
Work
What it is
Ref.
FastAPI backend template
Hybrid Interactive's official backend template: async SQLAlchemy 2.0 with Alembic, Celery and Redis for background jobs, and JWT authentication with role-based access control.
Deploys a containerized app over SSH to one server or several behind a load balancer, one host at a time behind a health check, and puts the previous release back if a host fails. Runs from GitHub Actions on every merge, from a laptop, or from a local control panel.
@misc{babu2026business,
author = {Babu, Amal},
title = {Software architecture, business systems and applied AI},
year = {2026},
howpublished = {\url{https://amal-babu-git.github.io/}}
}