Senior Backend Engineer (.NET 10)

We are building Yancu into a broader digital household-management platform that brings several products under one roof.

Role Description

You will join a small, energized founding engineering team as a .NET developer working end-to-end on the platform that powers comparison, switching, contract management, and the services we are layering on top of it. The work is hands-on: designing APIs, modeling domain logic, owning database schemas and migrations, integrating with regulator and supplier systems, and shipping services that real users depend on.

Expect day-to-day responsibility for:

- Designing and building .NET / ASP.NET Core services behind a Next.js frontend, contract-first via OpenAPI.

- Modeling the domain offers, contracts, identity, payments and translating it into code that the next engineer can extend without rewriting.

- Owning relational schema and EF Core migrations, including the queries those migrations have to live with in production.

- Working with OAuth 2.1 / OIDC and JWT-based auth against a real identity provider (Keycloak), in a regulated environment.

- Deploying and operating what you build Docker, CI/CD, cloud infrastructure not handing it to someone else.

- Talking directly to the founders and to users. Requirements arrive as conversations, not as Jira tickets. You are expected to push back, clarify scope, and propose better alternatives when you see them.

Qualifications

- Production .NET / ASP.NET Core experience you can defend in detail code you wrote, decisions you made, trade-offs you would now revisit.

- Strong C#: async, generics, nullable reference types, and the judgement to know when to stop being clever.

- Real Entity Framework Core: migrations under load, query tuning, reading the SQL EF actually emits.

- Working knowledge of a production relational database (PostgreSQL or SQL Server) beyond "add an index".

- HTTP API design experience, ideally grounded in OpenAPI / contract-first thinking.

- Comfort with Docker and at least one major cloud (Azure / AWS / GCP).

- Solid grasp of software fundamentals: OOP done with restraint, data structures, basic distributed-systems instincts.

- Fluent written English (most of our technical docs and code live in English).

- Bachelor's degree in Computer Science, Software Engineering, or a related field or equivalent demonstrable experience.

Qualifications

- Hands-on with OAuth 2.1 / OIDC + JWT in a real product (we use Keycloak).

- OpenAPI-driven code generation (NSwag, Kiota) and architectural-rule enforcement (NsDepCop, ArchUnit).

- CQRS / outbox / event-driven patterns shipped to production, applied with restraint.

- Infrastructure-as-code: Bicep, Terraform, or Pulumi.

- Background in a regulated domain energy, fintech, healthtech and the GDPR / PSD2 / PCI-DSS work that comes with it.

- Experience operating your own services in production, including incident response.

- Side projects, OSS contributions, or technical writing anything that shows how you think.

                                                   What we don't weigh heavily

- Years of experience as a number. Five years of the same year is not seniority.

- Whether you have shipped on our exact stack. We care that you can pick up a new tool fast and not get attached to the one you came in with.

- Big-name logos on a CV, unless the work behind them was real.