What you will do

• Design and deliver payment, ledger, wallet, payout, billing, or settlement services in TypeScript and Node.js.
• Model money using integer minor units, explicit currencies, rounding rules, value dates, and immutable postings.
• Implement idempotent APIs and effectively-once financial effects under retries and duplicate events.
• Integrate payment providers and banks through signed webhooks, asynchronous workflows, correlation identifiers, and recovery paths.
• Build reconciliation processes that identify matched, missing, duplicate, and mismatched records.
• Implement explicit lifecycle states for authorisation, capture, settlement, holds, fees, refunds, reversals, and disputes where relevant.
• Develop React and Next.js operational interfaces for investigation and controlled manual resolution.
• Write automated integration tests around transaction boundaries, concurrency, retries, and failure recovery.
• Establish observability and audit trails suitable for production financial operations.
• Participate in client discovery, explain trade-offs, estimate work, and review human- and AI-generated code.

Required experience

• 5+ years building and operating production backend or full-stack software.
• Strong TypeScript and Node.js, including API design, asynchronous programming, testing, and production debugging.
• Production experience with at least one genuine money path: ledger, wallet, acquiring, payouts, payment infrastructure, financial billing, or settlement.
• Strong PostgreSQL, SQL, data-modelling, and transactional-consistency skills.
• Practical understanding of idempotency, concurrency, webhooks, asynchronous processing, and partial-failure recovery.
• Experience building or maintaining React and Next.js applications.
• Production ownership including CI/CD, monitoring, incident investigation, and incremental delivery.
• Strong written and spoken English for client and team communication.

Useful, not required

• Double-entry accounting and derived-balance models.
• FX, multi-currency, card acquiring, PCI DSS, 3DS, or SCA.
• Transactional outbox, queues, workflow engines, or event-driven systems.
• High-volume reconciliation and settlement-file processing.
• Previous consultancy, outsourcing, or direct client-facing delivery.

What we offer

• Full-remote work with a flexible schedule outside agreed client and team overlap.
• Full-time independent-contractor engagement.
• 14 paid vacation days and 7 paid sick days per year.
• Official public holidays in your country of residence in addition to the paid days above.
• Work from your own laptop; EthBerry provides the project accounts and paid software licences required for the engagement.
• Compensation agreed individually based on relevant experience.
• Direct participation in architecture and technical decisions on client projects.
• The contract does not include health insurance, company hardware, or office-based benefits.

Hiring process

1. Application review.
2. HR screening — 30 minutes.
3. Technical and domain interview — 90 minutes. We discuss one production system and a real issue involving retries, balances, provider events, or reconciliation.
4. Unpaid take-home assignment — strictly capped at 4–6 hours. Implement a small NestJS and PostgreSQL payment flow with idempotent payment creation, immutable debit and credit postings, duplicate or out-of-order provider webhooks, and a reconciliation result for matched, missing, and mismatched records.
5. Assignment review — 75 minutes. You explain transaction boundaries, invariants, failure handling, tests, and trade-offs.
6. Final cultural-fit interview — 30 minutes.

AI coding tools are allowed. Their use must be disclosed briefly, and you must be able to explain and defend every submitted decision. The assignment is not used in production.