Senior Software Engineer

Senior Software Engineer

Department: Technology

Employment Type: Permanent - Full Time

Location: London

Reporting To: Mesut Kosucu

• This role sits in the Banking and FX tribe, which owns payment processing, FX pricing and trading, the ledger, reconciliation, bank integrations, FIX engine connectivity, payment compliance and the client portal. Between them, that covers the movement of client money end to end and everything clients see while it happens.
• You will be building services in .NET 10 on Azure, mostly asynchronous flows that have to stay correct when a banking partner times out halfway through or when the same message arrives twice. It's an end-to-end banking platform, so the work spans all of it rather than one corner: payments, FX, the ledger, reconciliation, integrations, compliance and the portal. Wherever it lands, getting it right beats getting it out.
• You make the design calls on your domain and argue them out with the tribe. You build it, you run it, you own it. Services stay with the engineers who wrote them, which means you're trusted to build them your way.
• The role is hybrid, with 2 to 3 days a week in our London office.

• Design, build and run services in .NET 10 on Azure, owning them from first commit through to production support.
• Build asynchronous flows that stay correct under partial failure, timeouts, retries and duplicate delivery.
• Work across the platform: payment processing, FX pricing and trading, the ledger and reconciliation, bank and scheme integrations, FIX connectivity, payment compliance and the client portal.
• Integrate with banking partners and payment schemes, including the parts of those integrations nobody documents.
• Make the architectural calls on your domain, write them down, and defend them in front of the tribe.
• Build in security, availability, reliability and observability from the start, and instrument your services so the answer to what's happening is already in a dashboard.
• Use AI tooling well. We use Claude Code daily, and we expect judgement about where it earns its place and where it doesn't.
• Review code, raise the standard around you, and help less experienced engineers get better

• Plenty of .NET behind you, and experience running your own services in production rather than shipping features into someone else's.
• Production experience on cloud platforms. Azure ideally, but similar experiences on AWS or GCP are just as valuable.
• Comfort with asynchronous, event-driven systems and the awkward parts that come with them: idempotency, ordering, retries, poison messages, exactly-once as a promise nobody can keep.
• Security, availability, reliability and observability built in from the start, not bolted on at the end. You think about who can reach what, you know how your service behaves when a dependency disappears, and you instrument it accordingly. We use Grafana and Application Insights. We hold client money, so this is the job rather than a preference.
• Real experience building software with AI, not just an interest in it. We want someone with a feel for when it helps and when it's quietly making a mess.
• Strong SQL Server, including query and schema work under real load, and strong familiarity with code-first ORMs, bonus points if its EF Core.
• Solid testing instincts and the ability to say what a piece of code is actually protected against.
• Comfortable working somewhere regulated, where changes to how money moves need evidence behind them.
• Clear communication with engineers and non-engineers, the willingness to disagree, and to commit once the call is made

• Payment processing systems
• Double-entry ledgers
• FX products and pricing
• Reconciliation and breaks
• Payment compliance
• Bank and scheme integrations
• FIX protocol and market connectivity

If you've done any of it, say so. If you haven't, we'd rather teach you that than compromise on the engineering.

• .NET 10, SQL Server and Azure, with the right tool for each job rather than a house framework for everything.
• Azure Dev Ops for planning and CI/CD.
• Grafana and Application Insights for observability.
• Claude…