Senior Back-End Developer

About The Company

Hercle is a fast-growing fintech building institutional-grade infrastructure that bridges fiat, stablecoins, and digital assets, enabling cross-border payments and banking infrastructure for global trade.

About The Company

Hercle is a fast-growing fintech building institutional-grade infrastructure that bridges fiat, stablecoins, and digital assets, enabling cross-border payments and banking infrastructure for global trade.

Serving over 200 clients globally, Hercle provides banks, brokers, payment service providers, fintechs, commodity traders, corporate treasuries, and other NBFIs with seamless solutions for cross-border payments and treasury management.

Working at Hercle

We're a lean, flat team where ideas matter more than titles and everyone gets real responsibility from day one. You'll solve complex problems at the intersection of global finance and digital assets, for some of the world's largest institutions and corporates. If you're curious, driven and excited to shape how money moves globally, we'd love to meet you.

About The Role

We're looking for a Senior Back-End Developer to join our Foundations & Reporting squad, which owns Hercle's technical foundations and information flow: the core ledger, balances, reconciliation and reporting, and the adapters that connect us to banks, custodians, venues and other providers.

Key Responsibilities

• Design, build and maintain the double-entry ledger and balance services that are Hercle's source of truth
• Scale the reconciliation engine that automatically matches our books against banks, custodians and venues
• Build resilient adapters to banking, custody, exchange and stablecoin providers, including webhooks and deposit processing
• Own the Reporting API and data feeds used by Finance, Data, auditors and regulators
• Drive platform reliability: uptime, monitoring, logging, tracing and alerting across services
• Write clean, documented code, review peers' work, fix bottlenecks and bugs, and improve CI/CD

How We Build

Every squad works on our two C# code bases: the Execution API, the client-facing gateway exposing documented REST and real-time WebSocket (SignalR) APIs, and the Back Office API, used daily by Operations, Compliance and the trading desk. Behind them sits a fleet of domain microservices and provider integrations.

• .NET 10 microservices over gRPC; event-driven internals with CQRS, domain events and background jobs
• AWS throughout: EKS, DynamoDB (in-memory caches on the hot path), Cognito, OpenSearch, S3
• Azure DevOps CI/CD, with integration tests run against real deployed environments
• AI-first engineering: agents write and refactor code, review every PR and help investigate incidents

What You Will Work On

You own the source of truth: what Hercle holds, where it holds it, and the systems that keep the two in agreement.

• Core ledger, balances and transactions services that every trade and payment writes to
• Adapters to banks, custodians, exchanges, stablecoin issuers and payment platforms
• Idempotent webhook ingestion and deposit processing, resilient to provider outages
• The reconciliation engine and position management system (PMS)
• Reporting API and data feeds, plus platform reliability on Kubernetes

Requirements

• Bachelor's degree in Computer Science, Engineering or a related technical field
• 5+ years building back-end systems in a strongly typed language (e.g. C#/.NET, Java, Kotlin, Go)
• Strong grasp of OOP, design patterns, distributed systems, concurrency, multithreading and performance optimisation
• Experience with SQL and NoSQL databases, CI/CD, Git and testing frameworks
• Strong problem-solving, attention to detail and ownership in a fast-paced environment
• Daily, hands-on use of AI coding agents on production work (not just autocomplete), with the judgement to give them the right context and to review and own what they produce
• Fluent written and spoken English

Nice to have

• Strong C#/.NET experience
• Knowledge of Ledgers, accounting, reconciliation or financial reporting systems, and financial controls and audit requirements in a regulated environment
• Experience with integrating custody, exchange or banking APIs and their webhooks
• Familiarity with observability and SRE practice (OpenTelemetry, Prometheus, Grafana, ELK or similar) on Kubernetes
• Experience with NoSQL data modelling (keys, secondary indexes, consistency) at production scale, ideally DynamoDB
• Experience with AWS (EKS, DynamoDB, Cognito, IAM) and Kubernetes in production
• Autonomy and ownership: you take loose prob