Freelance - Senior .NET & Azure Engineer

About the role

Zenchef acquired Formitable, a Dutch restaurant reservation platform that powers websites, widgets, payments, and marketing for thousands of restaurants across Europe.

The Formitable backend is a mature .NET system running on Azure — and every day, real restaurants depend on it for bookings, prepayments, and guest communications.

Our long-term contractor is retiring from freelancing, and we're looking for a senior backend engineer to take ownership of the platform.

The role splits between keeping the lights on (incidents, surgical fixes, careful production releases) and moving the platform forward (performance, stability, targeted features, platform upgrades).

This is a hands-on role with high autonomy and high impact.

You'll be the technical authority on the Formitable backend, working closely with our DevOps lead, the support team, and the wider product engineering org.

What you'll do

Production stewardship: Plan and execute releases to production, typically out of customer hours (releases usually go out late evening or around 2 a.m. CET to minimise blast radius). Own rollback strategies and smoke tests.

Performance and stability work: Identify and resolve issues currently degrading the platform — missing or wrong SQL indexes on hot tables, N+1 Cosmos queries, EF Core query plans that fall off the optimiser, queue back-pressure, retry storms.

Platform upgrade: Plan and execute upgrades to .NET, key NuGet packages (including private feeds), Azure services, and third-party integrations — without disrupting production.

Targeted feature development: Pick up scoped backend features and changes and ship them safely.

Internal tooling: Maintain and extend the Formitable admin site

Knowledge transfer: We want this role to actively reduce single-point-of-failure risk. You'll pair with internal engineers, walk them through the system as you fix things, and leave behind enough context — in code comments, PR descriptions, short notes — that the platform is operable when you're on holiday.

Tech stack

.NET / C# (modern versions), Entity Framework Core, ASP.NET Web APIs

Azure — App Service, Functions, SignalR Service, Service Bus / queues, Application Insights

SQL Server (Azure SQL) with EF Core, plus direct query and index tuning

Cosmos DB

GitHub (Actions, private NuGet feeds), pre-prod and prod environments

Mollie payments (Bancontact, iDEAL, cards) and other third-party integrations

What we're looking for

Senior C# / .NET backend engineer with deep Azure production ownership — ideally 8+ years where both the application layer and the cloud infrastructure are your domain. Azure is not a deployment target here — it's part of the system you own.

Azure platform depth. Hands-on production experience with App Service / AKS, Azure SQL, Cosmos DB, Service Bus, Application Insights, and Key Vault. You know how to right-size resources, contain costs, and respond to platform-level incidents — not just application-level ones.

Production maturity. Comfortable owning overnight releases, rollback plans, and the weight of a system where mistakes affect real restaurants in the morning service.

Diagnostic mindset. At home in Application Insights, SQL DMVs, Cosmos metrics, and logs. Able to find root causes in a codebase you didn't write, with significant historical complexity.

Genuine AI-assisted developer. You use Claude Code, Cursor, Copilot, or equivalent daily — not occasionally. You know where the guardrails matter in a complex codebase, and you bring that judgment, not just the tool.

Communication. Clear written English, transparent about risk, comfortable explaining technical trade-offs to non-technical stakeholders.

Nice to have

Experience with restaurant tech, reservation systems, or any high-concurrency consumer-facing platform with payment flows.

Experience leading the stabilisation or modernisation of a legacy .NET codebase.

Familiarity with Mollie or similar PSPs and EU payment methods (Bancontact, iDEAL, SEPA).

Dutch or French language skills (not required — working language is English).

Flexible engagement shape

We're open to different shapes for this engagement:

A fully async, daytime-only setup, with scheduled platform work and incidents handled during your working hours.

A heavier on-call commitment with extended-hours coverage, in exchange for a larger retainer.

We'll define this together based on what works for you.

Incident response expectations adapt accordingly.