Senior Back-End Developer (Payments)

As a Senior Back-End Developer at Hercle, you join the Payments squad, which owns the company's money journeys end to end. You design and build the systems that move money from A to B-deposits, withdrawals, transfers, transfer-outs and rebalancing-across fiat, stablecoins, and digital assets for over 200 clients globally, including banks, brokers, payment service providers, fintechs, and corporate treasuries.

What you'll do

• Design and build a scalable, event-driven payment orchestration engine for deposits, withdrawals, transfers and rebalancing
• Implement state machines, idempotency, retries and compensation so every money movement is safe, traceable and recoverable
• Integrate orchestration with account data, provider adapters (banks, custodians, exchanges) and the core ledger
• Build and operate the job fleet that automates rebalancing and recurring flows, with strong monitoring and alerting
• Work with product, Operations and banking infrastructure clients to remove manual steps and improve journey success rate and speed
• Write clean, documented code, review peers' work, fix bottlenecks and bugs, and improve CI/CD
• Own deposit, withdrawal and transfer flows over WebSocket and REST, including payees and crypto addresses
• Implement banking orchestration with one canonical model routing to banks, crypto custodians and Lightning
• Build the balance pipeline with reservations, ledger entries per change, and compensation on provider failure
• Handle async provider states via webhooks, retries and idempotency to ensure no payment is lost or executed twice
• Manage Operations flows including approvals, rebalancing across exchanges and accounts, and scheduled jobs

What you bring

• A Bachelor's degree in Computer Science, Engineering or a related technical field
• 5+ years building back-end systems in a strongly typed language (C#/.NET, Java, Kotlin, Go or similar)
• 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
• Familiarity with payment rails (SEPA, SWIFT, Faster Payments, on-chain and Lightning) and blockchain transactions, wallets and stablecoin transfers
• Experience with orchestration patterns such as sagas, outbox, compensation across several external providers, and message brokers (Kafka, RabbitMQ)
• Knowledge of double-entry ledgers and payment reconciliation, and hands-on experience with custody APIs
• Experience with AWS (EKS, DynamoDB, Cognito, IAM) and Kubernetes in production
• Autonomy 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
• Curiosity for finance, digital assets and the regulatory side of what we build
• Italian language skills

What we offer

• Competitive base salary of EUR 70,000 - 90,000, depending on experience
• Real ownership in a squad with a clear problem space, where you own what you ship from first idea to production
• Career growth and flexible remote/hybrid working in a collaborative, forward-thinking team

About Hercle

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. The company serves over 200 clients globally, including banks, brokers, payment service providers, fintechs, commodity traders, and corporate treasuries.