Senior Back-End Developer

h3About The Company /h3 pHercle 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. /p pServing 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. /p h3Working at Hercle /h3 pWe'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. /p h3About The Role /h3 pWe're looking for a Senior Back-End Developer to join our Payments squad, which owns Hercle's money journeys end to end. The goal: one unified way to move money from A to B (deposits, withdrawals, transfers, transfer-outs and rebalancing), whoever is sending and whoever holds the funds. /p h3Key Responsibilities /h3 ul liDesign and build a scalable, event-driven payment orchestration engine for deposits, withdrawals, transfers and rebalancing /li liImplement state machines, idempotency, retries and compensation so every money movement is safe, traceable and recoverable /li liIntegrate orchestration with account data, provider adapters (banks, custodians, exchanges) and the core ledger /li liBuild and operate the job fleet that automates rebalancing and recurring flows, with strong monitoring and alerting /li liWork with product, Operations and banking infrastructure clients to remove manual steps and improve journey success rate and speed /li liWrite clean, documented code, review peers' work, fix bottlenecks and bugs, and improve CI/CD /li /ul h3How We Build /h3 pEvery 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. /p ul li.
NET 10 microservices over gRPC; event-driven internals with CQRS, domain events and background jobs /li liAWS throughout: EKS, DynamoDB (in-memory caches on the hot path), Cognito, OpenSearch, S3 /li liAzure DevOps CI/CD, with integration tests run against real deployed environments /li liAI-first engineering: agents write and refactor code, review every PR and help investigate incidents /li /ul h3What You Will Work On /h3 pYou own every money movement on the platform, from the client request to the provider confirmation and the ledger entry. /p ul liDeposit, withdrawal and transfer flows over WebSocket and REST, incl. payees and crypto addresses /li liBanking orchestration: one canonical model routing to banks, crypto custodians and Lightning /li liThe balance pipeline: reservations, a ledger entry per change, compensation on provider failure /li liAsync provider states (webhooks, retries, idempotency): no payment lost or executed twice /li liOperations flows: approvals, rebalancing across exchanges and accounts, scheduled jobs /li /ul h3Requirements /h3 ul liBachelor's degree in Computer Science, Engineering or a related technical field /li li5+ years building back-end systems in a strongly typed language (e.g. C#/.
NET, Java, Kotlin, Go) /li liStrong grasp of OOP, design patterns, distributed systems, concurrency, multithreading and performance optimisation /li liExperience with SQL and NoSQL databases, CI/CD, Git and testing frameworks /liliStrong problem-solving, attention to detail and ownership in a fast-paced environment /li liDaily, 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 /li liFluent written and spoken English /li /ul h3Nice to have /h3 ul liStrong C#/.
NET experience /li liFamiliarity with payment rails (SEPA, SWIFT, Faster Payments, on-chain and Lightning) and blockchain transactions, wallets and stablecoin transfers /li liExperience with orchestration patterns: sagas, outbox, compensation across several external providers, message brokers (e.g. Kafka, RabbitMQ) /li liKnowledge of double-entry ledgers and payment reconciliation, and hands-on experience with custody APIs /li liExperience with AWS (EKS, DynamoDB, Cognito, IAM) and Kubernetes in production /li liAutonomy and ownership: you take loose problems to production in small, reviewable PRs, follow your code after release, write clearly, and work directly with Operations, Compliance and Finance /li liCuriosity for finance, digital assets and the regulatory side of what we build /li liItalian is a plus /li /ul h3Why join Hercle? /h3 ul liCompetitive base salary of EUR 70,