Senior Backend Developer
Level inferred from job title
Job description
Senior Backend Developer role focused on building the backend core of quinn ONE, a multi-country payroll and employment-administration platform. The role owns backend modules, the PostgreSQL data model, foundations, and production reliability end to end.
At a glance
- Employment
- Full-time · Employee (employment agreement)
- Work mode
- Hybrid · Zürich, Switzerland
- Languages
- English – fluent, German
What you'll do
- Design, build, test and run backend modules and the APIs they expose, from requirements to production, without waiting to be handed a ticket
- Own the PostgreSQL model the platform rests on: schema design, migrations, transactions, indexing, and the calculations that must be right to the cent
- Build the foundations: audit trail, logging, versioning of APIs and services, and the database upgrades that keep the platform current
- Ensure reliability and security in production: tests, observability, performance, and data protection by design; root causes, not symptoms
- Evolve the architecture pragmatically: module boundaries, dependencies, the shared core and the country layers, with clear trade-offs rather than fashionable patterns
- Raise the engineering bar: code review, design discussions, and mentoring developers in Zurich and the Armenia team
- Own everything behind the frontend: the domain model, the payroll logic, the APIs, the integrations with authorities, insurers and banks, and the data; agree the API contract with the Product Frontend Engineer
- Use AI tools daily to build leverage: scaffolding, test generation, migration checks, and removing manual work
- Deliver the platform's audit trail, tested and documented, within 100 days and fix the first risks spotted on arrival
- By month nine, be the person the team turns to for the quinn backend, with a mentored developer delivering features on their own
- By the end of the year, have major backend roadmap items live (logging, the database upgrade, versioning for APIs and services) and at least one introduced standard used beyond the team
What we're looking for
- Shipped and run production systems in C# and modern .NET / ASP.NET Core, and know how they behave under load
- Know PostgreSQL properly: schema design, transactions, locking, indexing and query optimisation; read the execution plan before adding a cache
- Designed APIs and modules with clear boundaries and manageable dependencies
- Treat personal and financial data with care; security is part of how you design, not a review at the end
- Use AI tools every day, and can show where they made you faster and where you caught them being wrong
- Own initiatives independently and raise risks before they become surprises
- Review constructively, mentor willingly, and write code others can take over
- English is your working language
Nice to have
- German is a plus
- Worked where an amount is either right or wrong: payroll, banking, insurance, accounting or tax
- Built foundations others relied on for years: an audit trail, observability, API versioning, a data model
- Taken a major database upgrade or migration through production without drama
- Can explain what you built, why you chose your approach, and what changed because of it
Your team
quinn ONE backend
The backend core of quinn ONE, a modular monolith in C#, .NET 10 and PostgreSQL serving the quinn app, Maestro for batch processing, and AI agents; works alongside a Product Frontend Engineer and an Armenia team.
How to get hired
- 1A 20–30 minute screening call
- 2An in-person interview in Zürich on your career so far
- 3A focused technical interview with the team (where we may work through a real quinn problem together)
- 4Reference calls
Apply
About ServiceHunter AG - quitt, quinn
Payroll that runs itself. You build the part that runs it.
quinn is an app-based managed payroll and employment-administration service for households and companies who employ people directly. The customer stays the legal employer; quinn registers the employment, runs payroll, pays salaries, social insurance and taxes, and handles every filing that follows, on their behalf and automated end to end. We don't sell payroll software. We run payroll.
Mission
Fair employment, for all.
Key facts
- Payroll and employment administration
- Operates in Switzerland, Germany and the UK
- Last year more than CHF 200 million in salaries ran through our systems, correct to the cent
- Building quinn ONE: one platform for every product and market, designed to carry twelve countries
- AI-native, operationally rather than as a slogan
- Has a team in Armenia