0007. Back end: .NET and ASP.NET Core

Status	Accepted
Date	2026-10-10
Deciders	Stuart Meeks

Context

Signboard is maintained in evenings and weekends, so the back end must be something the maintainer can debug quickly after a fortnight away ("boring technology" in the vision). The maintainer's deep experience is in .NET.

Decision

We will build the back end in C# on the current .NET long-term support release (.NET 10 at the time of writing), using ASP.NET Core for the HTTP API (ADR 0010) and Entity Framework Core for data access (ADR 0008). We will move to each new LTS release within six months of its release.

Options considered

1. .NET (ASP.NET Core): the maintainer's strongest skill; fast, mature, cross-platform, runs well in a small Linux container; first-class OpenAPI support. Chosen.
2. Node.js (TypeScript): one language across front and back end; less familiar to the maintainer, and a weaker standard library for domain-heavy code such as pricing.
3. Python (Django): excellent admin and ORM; unfamiliar to the maintainer.

Consequences

• The front end and back end are in different languages (TypeScript and C#). The OpenAPI contract is the bridge, and the TypeScript client is generated from it.
• Contributors need .NET skills for back-end work.
• Only LTS releases are used, so upgrades happen roughly every two years rather than every year.