Senior Software Engineer

Immersum; Greater London; Hybrid; GBP 85,000 - 125,000; Full time

Job summary

Immersum is seeking a Senior Software Engineer to design, build and run new services in .NET on Azure, in a London hybrid team. You’ll own from first commit to production, making architectural decisions and owning reliability in a high-volume FX/payments platform.

You’ll work with a fast-paced, autonomous team shipping changes frequently, ensuring correctness, security and observability while delivering robust services in production.

Qualifications

• Strong commercial .NET/C# experience.
• Experience building and running your own services in production.
• Experience working with cloud platforms - Azure preferred.
• Strong understanding of asynchronous/event-driven systems.
• Experience with reliability challenges including idempotency, retries, ordering and partial failure.
• Strong SQL Server experience, including queries and schema design under load.

Responsibilities

• Design, build and run new services in .NET on Azure.
• Own the service from design through production and deployment.
• Work across payments, FX, ledger, reconciliation, integrations and client portal.
• Collaborate with engineers to refine architectural decisions and maintain standards.
• Deliver high-quality, reliable services in a high-volume, fast-paced environment.

Skills

NET/C#

Production ownership

Cloud platforms Azure

Async/event-driven

Reliability & idempotency

SQL Server

High-volume transactions

Tools

EF Core

Azure

Job description

Role: Senior Software Engineer (.NET / Azure)

Location: London, hybrid (2-3 days per week in office)

Immersum are partnering with a rapidly growing Fintech business operating in the FX and payments space who are looking for a Senior Software Engineer to join an autonomous engineering team.

This is a role for someone who wants to build and own products from the ground up, rather than simply adding features to an established platform. You will have ownership from the initial design and first commit through to production, with the freedom to make architectural decisions and be accountable for what you build.

The Company:

This global Fintech business is transforming how businesses and financial institutions move money internationally. Operating across FX, payments and banking infrastructure, they are building a high-volume platform where reliability, scalability and correctness are critical.

The engineering environment is fast-paced and highly autonomous, with short paths between making a decision and getting it into production. Engineers are trusted to build, deploy and run the services they own.

The Role:

You will be responsible for designing, building and running new services in .NET 10 on Azure, working across payments, FX, the ledger, reconciliation, integrations, compliance and the client portal. This isn't a role where you'll spend your time working on an established product and incrementally adding features. They're looking for a builder who enjoys taking ownership of a problem, designing the solution, building it and getting it into production.

You'll be working in a high-volume, high-transaction environment where the pace of delivery is important. The ideal candidate will be comfortable working in an environment where teams are shipping new products and features 8-10 times a day, whilst maintaining the engineering standards required when you're moving real money.

You'll need to be comfortable owning your services in production and dealing with the difficult parts of distributed systems - failures, timeouts, retries, duplicate messages and integrations that don't behave as expected.

You will also have the autonomy to make architectural decisions within your domain, work closely with other engineers to challenge and refine those decisions, and ultimately build it, run it and own it.

Technology:

• SQL Server / EF Core

What they're looking for:

• Strong commercial .NET/C# experience
• Experience building and running your own services in production, rather than purely developing features within an existing environment
• Experience working with cloud platforms - Azure preferred
• Strong understanding of asynchronous/event-driven systems
• Experience with reliability challenges including idempotency, retries, ordering and partial failure
• Strong SQL Server experience, including queries and schema design under load
• A genuine builder mentality – someone who enjoys taking ownership from idea/design through to production
• Comfortable working in a fast-moving engineering environment with frequent releases and a high volume of transactions
• Strong engineering standards around testing, security, observability and reliability
• Comfortable making architectural decisions and taking accountability for the services you build

Experience within payments, FX, banking, ledgers, reconciliation or other financial systems would be useful, but isn't essential.

If you're a Senior Software Engineer who wants genuine ownership, enjoys building products from scratch and wants to work in an environment where what you build goes into production quickly, this could be a great opportunity to learn more.