Backend Engineer
Littlefish
Software Engineering
Highbridge, UK · Remote
Posted on Mar 27, 2026
About littlefish
We are a fast-growing fintech startup powering financial institutions across the African continent through our full stack enterprise platform. Proudly rooted in South African values but with a vision that transcends borders, we provide a single stack that powers merchant acquiring across payments, onboarding, engagement, commerce and operations.
Help us enable every enterprise, connect every merchant, and make every transaction intelligent. Your work will create lasting change in how financial services are delivered
Role Summary
The Senior Backend Engineer is responsible for designing, developing, and maintaining secure, cloud-native backend software solutions using .NET 9/ 10, MongoDB, and Kubernetes (GKE) with an AI first mindset. This role includes ownership of backend services, ensuring high‑quality, high-performing, scalable code, collaborating with cross‑functional teams, supporting deployment pipelines, and contributing to DevOps processes - particularly around Azure pipelines and deployments to GCP.
Key Responsibilities
Design, develop, and maintain backend software solutions using .NET 9/ 10.
Implement clean, testable APIs and microservices.
Investigate and resolve backend software defects and issues.
Database systems and query optimization (MongoDB)
Collaborate with cross‑functional teams to define and implement backend system requirements.
Provide technical backend support and guidance to other engineers.
Lead and mentor junior engineers in backend development best practices.
Keep up to date with emerging backend/backend‑adjacent technologies.
Apply best practices: immutability, DDD principles, SOLID, clean architecture.
Ensure strong ownership of reliability (SRE/DORA)
Backend Architecture & Development
Design and implement distributed microservices in .NET (.NET 9/10) with REST/gRPC APIs, message/event streaming, and strict API contracts, optimized for containerized deployment and horizontal scalability.
Data modeling & performance in MongoDB (indexes, sharding/ replica sets, transactions where applicable) with secure connectivity and encryption (TLS; consider CSFLE for sensitive fields).
Infrastructure as Code & CI/CD: Git‑based workflows, automated build/ test/ deploy pipelines, progressive delivery, and binary authorization for supply‑chain safety.
Cloud Platform (Multi Cloud) & Kubernetes Operations
Deploy, scale, and operate services on GKE using best‑practice security: Workload Identity, RBAC/least privilege, network policies, shielded nodes, and regular cluster/hardening updates.
Observability: implement SLIs/SLOs, error budgets, tracing, metrics, and logs (OpenTelemetry/gCloud stack) aligned to SRE principles.
Reliability Engineering (SRE) & Delivery Performance (DORA)
Drive service reliability with incident management, postmortems, capacity planning, and automation to reduce toil; measure and improve DORA metrics (deployment frequency, lead time, change failure rate, failed deployment recovery time).
Security and Compliance
Embed PCI DSS 4.0 controls across architecture and pipelines (network segmentation, encryption at rest/in transit, MFA, vulnerability scanning, audit trails), and partner with Compliance/QA for assessments (SAQ/ROC).
MongoDB in regulated contexts: leverage Atlas PCI DSS posture, private endpoints/VPC peering, and field‑level encryption for cardholder data.
Cloud Cost Accountability)
Apply Kubernetes cost management practices (namespace/label taxonomy, request/limit hygiene, chargeback/showback dashboards).
Skills and Qualifications
7+ years backend engineering experience.
Deeply enthusiastic about AI
Strong proficiency in .NET 9/1 0.
Experience with MongoDB (schema design, indexing, performance).
Production experience with Kubernetes (preferably GKE).
Strong GCP/ Multi Cloud experience (Pub/Sub, Cloud Run, GKE, Cloud Monitoring).
Experience with event‑driven systems.
CI/CD experience (GitHub Actions, GitLab CI, Cloud Build).
Payments, fintech, banking integrations experience.
PCI compliance knowledge beneficial
Dash0 reporting experience beneficial
To apply, please send your resume and a short cover letter to talent@littlefishapp.com
