Senior Backend Engineer

Saturn; Greater London; Hybrid; GBP 110,000 - 140,000; Full time

Benefits offered by this job

Competitive salary

Equity package

Office in London

Dental and medical insurance

Learning budget

Gym and wellness center

Collaborative team

Job summary

Saturn is seeking a Senior Backend Engineer to own substantial backend systems from design through production. You will work with product, AI, and domain experts to build a durable platform that supports AI-driven advisory workflows and regulatory compliance.

You will contribute to event-driven architectures, robust data models and reliable integrations, ensuring correctness, observability and scalable operations for complex financial services platforms.

Qualifications

• 5+ years building backend systems with ownership of a substantial service.
• Deep experience with Go and TypeScript in production environments.
• Distributed systems using Kafka or equivalent with replay and idempotency.
• Strong data modelling across SQL and NoSQL with clear APIs.
• Design for correctness, resilience, and observability in large systems.
• Own production services, incidents and rapid improvements.
• Ability to write clear design docs and mentor others.

Responsibilities

• Event-driven architecture and Kafka-based workflows with retries and partial failures.
• Core data models spanning clients, households, assets, and advice.
• Ingestion and synchronization across CRMs and financial platforms with reconciliation.
• Backend services powering Saturn’s automated compliance and advice products.
• Interface between backend systems and Saturn’s AI platform for context and tools.
• Ensure correctness, auditability and traceability of financial workflows.
• Production ownership: observability, alerts, incident response, scalability.
• Develop shared libraries, patterns and set design review standards.

Skills

Backend systems

Go & TS

Kafka / Event-driven

Data modelling

Observability & reliability

Delivery in months

Production ownership

Written communication

Job description

Saturn is a Series A-backed fintech transforming how financial advice is delivered.

We operate in one of the world’s largest industries. Wealth and asset managers oversee more than $100 trillion and generate over $1 trillion in annual revenue, yet much of the infrastructure used to manage that wealth remains fragmented, manual and institution-specific.

Saturn is starting with the productivity and compliance systems used by financial advisers.

Our story

Saturn joined Y Combinator in 2024 and became one of the fastest-growing B2B companies in its batch.

We grew organically to a meaningful share of the UK financial advice market before acquiring the legacy leader, one of the industry’s most established compliance rule engine and suitability businesses, in 2025.

That acquisition combined AI-native product engineering with more than two decades of regulatory expertise, proprietary compliance logic and deep industry distribution.

Within two years of launch, Saturn became the leading provider of AI transformation to UK financial advice firms, supporting more than 9,000 regulated advice professionals who manage about $500bn in assets.

We have proved distribution, trust and demand. The most important infrastructure is still ahead of us.

Your role

As a Senior Backend Engineer, you will own substantial backend systems and platform capabilities, from design through to reliable operation in production.

Saturn is a Series A, Y Combinator-backed company building the AI-native operating system for financial advice. Our platform combines a living data model of the client, AI agents that complete complex advice and operational workflows, and compliance logic embedded directly into how work is produced. You will work with product engineers, AI engineers, domain experts and engineering leadership to turn complex financial and regulatory problems into durable systems.

You will not wait for problems to arrive as complete technical specifications. You are expected to understand the business outcome, find the constraints that actually matter and make sound trade-offs, protecting the integrity of the system without adding complexity that buys nothing. Shipping backend code is not the point. Your work decides whether Saturn is a collection of useful applications or a platform the company can safely depend on as the work becomes more important and more complex.

The Team

Our engineers care deeply about craft, speed and quality. They include early and founding team members from companies including Rippling, Postman, Gojek, CRED and Slice. You will work alongside product engineers, AI engineers, designers and Saturn’s domain experts: chartered compliance officers and paraplanners with decades of experience in financial advice. We are deliberately building a small, high-calibre engineering organisation for people who want genuine ownership, hard technical problems and the chance to shape an important company while its foundations are still forming.

What You’ll Work On

• Event-driven architecture and Kafka-based workflows , including long-running processes that behave correctly under retries, replay and partial failure
• Core data models spanning clients, households, firms, assets, products, advice and evidence, modelled clearly enough to be relied on across the platform
• Ingestion and synchronisation across CRMs, platforms, providers and financial systems, with reconciliation that makes external data accurate, current and usable
• The services behind Saturn’s automated compliance and advice products , including permissions, policy enforcement and firm-specific configuration
• The interface between backend systems and Saturn’s AI platform , supplying reliable context, tools and execution capabilities to agents
• Correctness, auditability and data integrity across financial workflows, so material actions remain traceable long after they happen
• Production ownership : observability, alerting, incident response, performance and scalability for the services you build
• Shared backend libraries, patterns and platform capabilities , plus technical direction, design and code review standards, and mentoring within your area

What We’re Looking For

• Backend experience in production. 5+ years building backend systems, including ownership of a substantial service or platform capability from design through to operation
• Strong command of Go and TypeScript , or comparable depth in another language and the appetite to work in both
• Distributed and event-driven systems. Strong understanding of Kafka or an equivalent, including ordering, replay, idempotency and partial failure
• Data modelling judgement. Experience modelling complex or data-critical systems across SQL and NoSQL, with a clear sense of APIs, service boundaries and data contracts
• Designing for correctness, resilience and observability , and building reliable integrations with external systems you do not control
• Delivery at scale of months. A record of scoping and delivering work measured in months against a business or product objective, with comfort owning decisions under incomplete information and real deadlines
• Operational responsibility. You own services in production, investigate incidents properly and turn what you learn into better architecture rather than another runbook
• Strong written communication. You write clear design documents for consequential systems, mentor engineers and raise the standard of design review, testing and operations around you

Preferred

• Building software for financial services or another regulated domain, ideally financial advice, wealth management or investment products
• Systems that hold, transact or manage money: ledgers, payments, custody, portfolio systems or financial reconciliation
• Long-running workflow engines or orchestration systems
• Building systems subject to compliance, audit or regulatory scrutiny
• Meeting enterprise security requirements such as SOC 2 and client due diligence questionnaires
• Taking backend systems from early production use to significant scale

What We Offer

• Competitive salary with regular appraisals
• Competitive equity package at an early stage company with high growth potential
• Our beautiful new five-floor office, "The Dome", equipped with an onsite gym and roof terrace
• Best-in-class dental and medical insurance
• A dedicated budget for learning and professional development
• Access to an additional world-class gym and wellness centre two minutes from the office
• A tight-knit, ambitious team that cares deeply about quality and each other