Case study · HOS
Rebuilding a single hospital system into a multi-tenant SaaS backend
HOS started as a hospital and room management system. It was rebuilt into a multi-tenant SaaS backend capable of powering multiple industries — the same architecture behind BitBuilder ERP.
- Origin
- Hospital / room management system
- Evolved into
- Multi-tenant SaaS backend
- Currently powers
- School ERP (Angular frontend)
- Built by
- BitBuilder’s founder, solo
01 · The problem
A system built for one organisation.
HOS was originally designed to run a single hospital. Offering it to more organisations would have meant a separate deployment for each client — duplicated infrastructure, manual set-up for every new customer and a growing maintenance burden.
To serve many organisations safely, the system needed strict separation of each client’s data, a way for new organisations to join without developer involvement, and authentication that could handle multiple organisations and roles.
02 · The solution
Re-architected as a multi-tenant platform.
The backend was rebuilt on ASP.NET Core and SQL Server so a single deployment can serve multiple organisations, with every record scoped to the organisation it belongs to.
- ASP.NET Core (C#)
- SQL Server + ADO.NET
- Angular (frontend integration)
- Multi-tenant architecture
03 · Key features
What was built.
One backend, many organisations
A single backend serves multiple organisations — each with its own isolated data — without spinning up new infrastructure per client.
Data isolation at the data layer
Every organisation’s data is scoped and isolated, so one client can never see or touch another client’s records.
Self-service onboarding
New organisations can register themselves instead of a developer manually provisioning each one.
Hardened authentication
Authentication was rebuilt to support multiple organisations and roles safely within the same system.
04 · The outcome
Actively built, actively used.
- HOS is the backend already wired to a school management ERP built in Angular.
- Multiple organisations can run on the same backend, each with isolated data.
- New organisations can onboard themselves without manual provisioning.
- Its multi-tenant architecture is the foundation BitBuilder’s industry ERP modules — hospital, school, hospitality, gym, salon and retail — are designed to build on.
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