Fractional Fintech Backend Engineer

Location: London

Salary: Competitive

Job Type: Fractional, 1-2 days per week

About The Company:

Our client is an early-stage financial technology business building an intelligent platform that combines secure financial processing with advanced data and AI capabilities. Accuracy, auditability and transaction integrity sit at the heart of the product.

The business is now looking for an experienced backend engineer to help create the core financial engine and establish a robust technical foundation for future development and scale.

Fractional Fintech Backend Engineer - The Role:

The Fractional Fintech Backend Engineer will design and build the core ledger and financial processing services using Go. The role will involve creating deterministic, event-sourced systems that ensure financial transactions remain balanced, traceable and safe.

Working directly with the founder and alongside graph, AI and infrastructure specialists, the successful candidate will translate complex accounting requirements into secure, maintainable software and reliable integrations.

Fractional Fintech Backend Engineer - Key Responsibilities:

• - Design and build an append-only, event-sourced double-entry ledger using Go
• - Develop strict, type-safe validation logic that ensures financial transactions balance before execution
• - Create secure, high-performance APIs and microservices for financial data and open banking integrations
• - Build reliable processes for idempotency, reconciliation, audit trails and transaction safety
• - Manage low-latency communication between backend services, graph databases and AI components
• - Establish engineering patterns for security, automated testing, observability, resilience and maintainability
• - Work closely with financial and product specialists to convert complex accounting requirements into clear technical solutions
• - Provide senior technical guidance while remaining closely involved in hands-on implementation

Fractional Fintech Backend Engineer - You:

• - Significant commercial experience developing concurrent, high-throughput backend services using Go
• - Strong fintech experience gained within banking, payments, open banking, accounting software or another transaction-intensive environment
• - Thorough knowledge of event sourcing, double-entry ledger concepts, idempotency, reconciliation and transaction safety
• - Excellent API, database, distributed systems and automated testing fundamentals
• - Strong understanding of security, data protection and auditability when handling sensitive financial information
• - Comfortable working with ambiguity, taking ownership of architectural decisions and explaining complex technical issues clearly
• - Experience with PostgreSQL, Neo4j, GCP, Moneyhub or similar financial data integrations would be advantageous

Fractional Fintech Backend Engineer - Benefits:

• - Competitive remuneration for a fractional commitment of 1-2 days per week
• - Opportunity to build the core financial engine of an innovative early-stage platform
• - Flexible working arrangements with London listed as the role location
• - A high-impact role combining architectural ownership with hands-on engineering