Tersago IT is the independent software consultancy of Nathan Tersago — building and modernising the systems businesses actually run on: SaaS platforms, point-of-sale, cloud infrastructure and the integrations in between.
The human behind the terminal. I've spent my career inside production systems — writing C# and TypeScript, but also onboarding the customers, taking the support calls and answering for what I ship. That full loop is the whole philosophy: software gets better when the person who builds it also has to sell it, run it and stand behind it.
Tersago IT is that loop, offered as a service.
From first architecture sketch to production on-call — no hand-offs, no telephone game between "the dev team" and "the business".
Multi-tenant platforms built end to end: backoffice, web shops, public APIs, kiosks. Architected for hundreds of tenants without hundreds of headaches.
Live migrations with zero drama — database engines, frontend frameworks, or whole hosting architectures swapped out while the business keeps trading.
Desktop point-of-sale where software meets the physical world: fiscal compliance devices, scales, payment terminals, printers — certified, signed, deployed.
Containerised workloads on Kubernetes, envelope-encrypted secrets, CI/CD pipelines and the Linux servers underneath — run like infrastructure, not folklore.
OAuth 2.0 partner APIs, Peppol e-invoicing, payment providers, vending machines, document exchange between systems that were never meant to talk.
A second brain for technical decisions: audits, build-vs-buy calls, identity strategy, and designs favouring explicit code over framework magic.
Recent engagements, anonymised where clients prefer it that way.
Core engineering on a Belgian SaaS ERP serving 200+ businesses: point-of-sale, B2B/B2C web shops, backoffice, self-scan kiosk and a public partner API — including cross-tenant order exchange built on an outbox/inbox pattern.
A landscape of 100+ per-customer on-premise services re-architected into a single multi-tenant cloud platform — tenants migrated wave by wave into a running production environment, with no downtime windows and no big-bang cutover.
SQL Server to PostgreSQL on EF Core, and an ASP.NET MVC + jQuery backoffice rebuilt in React + TypeScript — both carried out in parallel while the platform stayed live and kept shipping features.
UBL XML invoice generation and Peppol network delivery ahead of Belgium's e-invoicing mandate, plus an OAuth 2.0 public API with API-key storage secured by AWS KMS envelope encryption.
Chosen for longevity, not novelty — explicit code over magic, boring where boring wins.