Solo builder based in Cape Town. Mobile apps, web platforms and data tools — built from scratch, without agency overhead, and still working six months after handoff.
Each project built solo — from brief to production — with real users, real data and real consequences if it breaks.
Open water crossings in Cape Town involve cold Atlantic water (12–16°C), tidal streams, wind-driven currents and significant pace degradation over distance. No existing tool combined all these variables for personalised predictions.
A multi-variable prediction engine from scratch — integrating live tidal feeds, Open-Meteo marine data, cold water pace penalty curves and GPS-calibrated feed-stop modelling. No vendor. No off-the-shelf model.
"5:23:30 — your app in 1m:30sec out. Bloody unbelievable. You are a GURU of note."
Open water swimmer — immediately after completing her 15km Robben Island double crossing
Tidal current modelling · cold water pace penalty · feed stop intervals · calibrated on elite athlete GPS data from real crossings
South Africa's open water swimming community had no platform for real-time conditions, group coordination or community tracking. Just WhatsApp groups and word of mouth.
SwimLoading — a React Native app with live conditions, GPS swim logging, group coordination, leaderboards, safety screens and race organisation. Self-funded, zero marketing. Built and shipped solo.
"Dave Welensky verifying my day conditions with an unbelievable app — check it out swimmers."
Yolanda Carstens — open water swimmer, posting about SwimLoading to the SA community
A large South African retailer was migrating to SAP S/4HANA with 200,000 master data records across 993 columns. Data quality failures reaching production on go-live day would mean costly fixes under maximum pressure.
A proprietary data quality engine from scratch — no vendor, no off-the-shelf tooling. Runs daily in production, surfaces every failure and assigns it to a business owner for remediation before it gets anywhere near the new system.
I'm a solo builder — not an agency — which means you work with the person who makes every technical decision, writes the code and is still reachable six months after you've gone live.
Background spans enterprise SAP data engineering at scale — lead on Africa's largest SAP Retail rollout — to consumer mobile apps with real user traction built and grown solo. I know what it takes to get software from idea to production and keep it there.
Based in Cape Town. Available for contract builds from early brief through to deployed, stable and working.
App that needs building, a system that needs untangling, or a data problem that needs solving. I work on a contract basis — from brief to production-ready.
dave@apploading.co