Software Engineer (Backend) — Staff / Senior

United States Digital Space LLC; Greater London; On-site; GBP 120,000 - 180,000; Full time

Benefits offered by this job

Equity

Job summary

United States Digital Space LLC in London seeks a senior-to-staff backend engineer who owns the core systems behind every viewing, tenancy, certificate, rent payment and repair. You drive architecture, set patterns and raise the bar for correctness, reliability and scale in money-moving software.

The role requires real production systems experience, strong API/data modelling, and a track record of guiding other engineers.

Qualifications

• 6+ years building and operating production backend systems (more, for staff).
• Fluency in at least one backend language and framework, and the range to reason about system design — services, data models, APIs, failure modes.
• Real distributed-systems experience: eventual consistency, idempotency, concurrency, and their failure modes at production scale.
• Strong API and data modelling (document or relational), plus cloud / containerised deployment (GCP or AWS, Docker, Kubernetes).
• AI-Native engineer: you use AI across all layers of your work and utilise models expertly while understanding LLM failure modes and patterns.
• Senior: a track record of designing systems other engineers built on, and of raising a team's standard.
• Staff: you've set technical direction across several services or teams, and you're the person others escalated to when it's hard.

Responsibilities

• Own backend systems and architecture across the product.
• Define patterns and set standards to raise the bar.
• Ensure money movement and financial correctness in live systems.
• Lead event-driven coordination across services.
• Scale systems to handle thousands of concurrent journeys.
• Integrate AI-native approaches while maintaining guardrails.

Skills

Backend development

Distributed systems

API design

Cloud deployment

AI integration

Tools

MongoDB

GCP/GKE

Docker

Kubernetes

Pub/Sub

Job description

The role

You'll own the backend systems the company runs on — and the architecture other engineers build on: the software behind every viewing, tenancy, certificate, rent payment and repair. These are systems where correctness, reliability and scale are non-negotiable: real people's money, homes and legal exposure are on the line.

This is a senior-to-staff hire. At senior you own systems others build on — you make the architecture calls, set the patterns, and raise the bar around you. At staff you own the technical direction of a domain: you decide what gets built and how, you unblock other engineers, and you answer for how those systems behave under load.

What you'll work on

• Money movement. Rent, deposits and payouts through pooled client-money accounts — idempotent processing, split-settlement, exactly-once across service *and* bank boundaries.
• Reconciliation & bookings. A penny-accurate, self-healing ledger reconciling bank activity across thousands of tenancies; contended scheduling — viewings, certs, photography, maintenance against finite slots and vendor availability.
• Event-driven consistency. Services coordinating over Pub/Sub — sagas across offer contract tenancy payment with no distributed transaction to lean on. LLM tool calling, deterministic API calls, and other intra- and inter-service communications all running across the same coordination system.
• AI harnesses in production. Deploying agentic AI into real-world operational settings — acting on real money, tenancies and legal exposure, with the guardrails, observability and correctness that demands. Non-deterministic LLM working within compliant, secure deterministic software.

Our stack

We build on NestJS + TypeScript on GCP / GKE, with MongoDB, Redis and GCP Pub/Sub.

You don't need to arrive fluent in it. We hire strong backend engineers've built production systems with any robust framework — Java/Spring Boot, Go, Kotlin, C#/.NET, Python (Django/FastAPI) or Ruby on Rails — and can ramp into TypeScript fast. We care that you've built and operated real backends, not which language you did it in.

How we build

Small, well-factored services. TDD and DDD as defaults. Trunk-based CI/CD — you ship to production and own it, with tests, observability and clean rollbacks. Lean frameworks, readable code, and we move fast *because* the tests and boundaries let us.

What we're looking for

• 6+ years building and operating production backend systems (more, for staff).
• Fluency in at least one backend language and framework, and the range to reason about system design — services, data models, APIs, failure modes.
• Real distributed-systems experience: eventual consistency, idempotency, concurrency, and their failure modes at production scale.
• Strong API and data modelling (document or relational), plus cloud / containerised deployment (GCP or AWS, Docker, Kubernetes).
• AI-Native engineer: you use AI across all layers of your work and utilise models expertly while understanding LLM failure modes and patterns.
• Senior: a track record of designing systems other engineers built on, and of raising a team's standard.
• Staff: you've set technical direction across several services or teams, and you're the person others escalated to when it's hard.

Nice to have

• MongoDB and GCP/GKE.
• Event-driven architecture and message brokers (Pub/Sub, Kafka).
• Payments, ledgers, reconciliation, or another money-movement / financial-correctness domain.
• Fintech or another regulated, high-trust environment.

Who does well here

• You're precise about correctness — these systems move money; "mostly right" fails.
• You own the outcome, not the ticket — start to production, without being chased.
• You make the next engineer faster — clear code, clear reasoning.
• You want the hard problems — and you raise the standard around you.

Why apply

the company is the AI-Native operating company built for the home. We believe the home will be autonomously run by AI and we're building the software that will run all rental properties end-to-end, starting with London (the world's 2nd largest rental city).

The backend at the company is technically difficult on purpose: messy operational reality that doesn't fit clean schemas; money moving across financial rails where being wrong is not an option; high throughput across thousands of concurrent journeys; and a large surface serving many user types with different needs, permissions and trust levels. Every the company customer is served by the system you build, and the work compounds — every service and primitive keeps producing value after you ship it.

We've raised a $4m pre-seed from investors who've built the financial and operational infrastructure that moves billions and serves millions. They backed us because the home is the largest consumer asset where that infrastructure hasn't been built yet. You'll get competitive base pay, meaningful equity, and a small, high-agency team rebuilding an industry and growing at >100% month-over-month. We're hiring to facilitate this aggressive growth.