Python Backend Engineer | Payments & API Integration

Hlongwane
Lasie.

I build and operate production Python backends: REST APIs, payment integrations, database-driven platforms and cloud deployments. My strongest work is in payment engineering (Yoco, Paystack — webhooks, verification, subscriptions) and shipping systems that stay reliable in production.

I designed and currently operate KALXA, a live Flask/PostgreSQL platform handling business profiles, event ticketing, payments and multi-role access control — end to end, from data modelling to deployment and troubleshooting.

Python Flask / FastAPI PostgreSQL / SQLAlchemy REST APIs Payment Integrations Production Deployment
Selected Engineering Work

What I've Built

Production systems I designed, shipped and maintain — with an emphasis on backend architecture, payment reliability and operating software in production.

KALXA

Multi-feature Flask platform · Live in production

Featured Project — Backend & Platform

KALXA is a live, multi-feature platform I designed, built and operate end-to-end. It combines business profiles, event ticketing, reviews, media uploads and admin dashboards on a single Flask/PostgreSQL backend, with real payment processing and role-based access control.

Yoco & Paystack payment flows
Webhook verification & transaction checks
Unique ticket codes & scanning workflow
Multi-role access control
PostgreSQL schema & migrations
Production deploy (Render + Neon)

Engineering Notes

  • Backend: Flask + SQLAlchemy, modular blueprint structure separating public site, admin, payments and authentication.
  • Payments: Payment initiation, webhook receipt, signature/transaction verification, subscription state enforcement and access gating.
  • Data: Normalised PostgreSQL schema covering businesses, events, tickets, reviews and media; migration-managed via SQLAlchemy.
  • Deployment: Render-hosted app with Neon-managed Postgres, Cloudinary for media, custom domains and DNS managed directly.
  • Operations: Production troubleshooting of deployment, DNS and network issues; log review and reliability fixes.
Components of the KALXA Platform

Each module runs on the same backend architecture, with its own feature surface and access rules.

Ticketing & Business Profiles

Events · Payments · Scanning

Business & Event Platform

Digital Business Profiles & Ticket Sales

Businesses and restaurants create online profiles and promote experiences, while event organisers sell tickets online. Each purchase generates a unique ticket code and supports scanning at event entrances for secure check-in.

FlaskSQLAlchemyPostgreSQL YocoPaystack
Visit Platform

KALXA News Hub

Local Publishing

Digital Publishing

Local Stories & Business Visibility

A publishing module focused on local businesses, events and creators. Backend publishing workflows and article management help businesses and personalities gain visibility through digital content.

FlaskPostgreSQLArticle CRUD
Read KALXA News Hub

Creator Management Tool

Creator Workflows

Creator Tooling

Management & Monetisation Workflows

A creator-focused application designed to support content creators with professional management and monetisation workflows, built on the same Flask/PostgreSQL stack.

FlaskPostgreSQLAuth
Explore
Standalone Products

FinTech & Business Automation

Applications built to simplify financial workflows, business administration and reporting — deployed and accessible live.

VAT & PAYE

Financial Compliance Application

FinTech · Live Application

VAT & PAYE Compliance App

Brings VAT calculations, PAYE processing, payroll-related compliance workflows, reconciliation and financial reporting into a single application — simplifying essential financial processes for businesses.

PythonStreamlitFinancial Logic
Launch App

Financial Statement Generator

Financial Reporting

FinTech · Live Application

Digital Financial Reporting

Focuses on making financial information easier to process and present through structured reporting workflows.

PythonStreamlitReporting
Launch App
Technical Stack

What I Work With

Grouped by how deeply I use each technology, not just what I've touched.

Core

Day-to-day

Python · Flask · SQLAlchemy
PostgreSQL · REST API design
Payment integrations (Yoco, Paystack)
Webhooks · Auth & access control
Git / GitHub

Payment Engineering

Specialist area

Payment initiation & return flows
Webhook handling & verification
Transaction & subscription state
Access gating on payment status
Idempotency & retry patterns

Backend Frameworks

Working

Django & DRF
FastAPI
Blueprints & modular structure
Background processing basics

Frontend

Working

HTML5 · CSS3 · JavaScript
Bootstrap · Responsive design
Streamlit (internal tools)
React (exposure)

Databases

Working

PostgreSQL · SQLite · MySQL
SQL Server (exposure)
Schema design & migrations
Query optimisation basics

Cloud & Deployment

Working

Render · Neon · Cloudinary
Microsoft Azure (App Services, Functions, Azure SQL)
Domain & DNS configuration
Cloudflare · VPS hosting

AI Integration

Growing

LLM API integration
Retrieval-augmented features
Application automation

Earlier Work

Previous Projects

Applications that contributed to my experience across healthcare, e-commerce, APIs and backend tooling.

Rapha Healthcare Services web application

Rapha Healthcare Services

Healthcare website and web application supporting clinic administration, patient interactions, doctor management, clinic administrators and centralised superadmin operations. Included backend article publishing, announcements and patient enquiry workflows.

View on GitHub
Clinic appointment management system

Clinic Appointment System

Digital appointment management solution supporting healthcare service providers and streamlining clinic appointment processes.

View on GitHub
REST API blog project

Blog REST API

Backend blog API built with Python and Django REST Framework, demonstrating API design, serializer-based data handling and backend application structure.

View on GitHub
E-commerce website

E-commerce Platform

Responsive e-commerce website for a fruit and vegetable business — product presentation, shopping cart, authentication and a mobile-friendly shopping flow.

View on GitHub
About Me

Engineering with Ownership.

I'm a Python backend engineer who builds and operates production systems — not prototypes. My work spans REST API design, payment integrations, database engineering and cloud deployment, and I'm comfortable owning a system from data model through to the production issues that show up after launch.

The clearest example is KALXA, a live platform I designed and continue to run: a Flask/PostgreSQL backend with Yoco and Paystack payments, webhook verification, multi-role access control and production deployment on Render and Neon. Before that, I worked on Python/Django backends in healthcare administration and cloud deployments on Azure.

I'm currently deepening my work in agentic and LLM-based backend integration — building AI features into production systems with the same attention to reliability, cost and failure handling that payments demand.