Back-end Engineer - Crypto and Payments

As a Back-end Engineer on GoTymeX's Core Backend team, you will build the financial ledger, posting, reconciliation, and financial-control capabilities for a stablecoin and digital-assets wallet serving customers across South Africa, Asia, and Africa. You'll work on an online transactional core that must stay correct across vendor events, internal state, on-chain settlement, fiat payment rails, card settlement, fees, FX, holds, and operational exceptions.

What you'll do

• Build and improve an event-sourced, append-only double-entry ledger and its account, journal, posting, balance, hold, fee, FX, and adjustment models
• Implement posting rules and invariants that keep journals balanced, prevent unauthorised value creation or loss, and provide a clear audit trail
• Build transaction-processing flows for authorisation, holds, capture, settlement, reversals, refunds, chargebacks, expiry, corrections, and controlled manual adjustments
• Apply idempotency, deduplication, sequencing, and concurrency controls to payment, card, custody, and blockchain events that may arrive late or more than once
• Build reconciliation controls across the managed CASP ledger, Fireblocks, on-chain data, fiat ramps, card processing, treasury and accounting systems, and GoTyme's financial-control projection
• Build operational workflows for missing events, duplicate notifications, amount or currency mismatches, unbalanced postings, and suspense or repair processes
• Contribute to event schemas, financial data contracts, versioning, replay, and backfill approaches that preserve the audit trail without corrupting balances
• Work with finance and treasury to create accounting evidence, GL exports, reserve and liquidity views, and material for audits and regulators
• Apply strong practices for schema design, migrations, indexing, partitioning, data retention, backups, recovery testing, and database performance
• Take part in financial-core technical design and code reviews, sharing what you learn about ledger modelling, database correctness, and safe production practices
• Own monitoring and production support for the components you build, contributing to reconciliation service levels, incident response, root-cause analysis, and controlled remediation

What you bring

• 5+ years of backend engineering experience, including meaningful hands-on work on payments, ledger, accounting, settlement, core banking, or another high-integrity transactional system
• Experience building, operating, or making substantial contributions to a double-entry ledger, payment posting engine, settlement platform, core-banking subsystem, or equivalent financial system of record
• Strong relational database and SQL skills, ideally PostgreSQL or MySQL, with deep understanding of schema modelling, transaction isolation, locking, concurrency, query performance, indexing, migrations, and recovery
• Working understanding of journals, debits and credits, chart of accounts, posting rules, available versus settled balance, holds, reversals, adjustments, fees, FX, and reconciliation
• Practical experience with idempotency, outbox and inbox patterns, event ordering, duplicate delivery, exactly-once-effect design, and failure recovery
• Experience building reconciliations that compare internal and external records, identify breaks, retain evidence, and support controlled repair
• Strong Java or Python experience and a track record building and operating reliable production services
• Experience with event-driven systems, including event replay, schema evolution, auditability, and eventual consistency
• Clear technical communication to work with finance, product, compliance, and operational partners to turn requirements into precise models and implementation decisions

Nice to have

• Experience in stablecoins, digital assets, crypto custody, exchange operations, or on-chain settlement
• Experience reconciling custody or ledger records to blockchain transaction events, confirmations, fees, and failed transactions
• Experience with Fireblocks, TigerBeetle, Modern Treasury, Mambu, Temenos, or similar financial-ledger or custody infrastructure
• Experience in card issuing or processing, payment acquiring, cross-border payments, treasury, FX, or regulated banking
• Experience with AWS serverless and event-driven services such as Lambda, EventBridge, SQS, and Step Functions, or Kafka as the selected event platform
• Experience designing data retention, partitioning, archival, and disaster-recovery approaches for financial records
• Experience with accounting exports, general-ledger integration, audit evidence, regulatory evidence, and operational controls
• Experience mentoring other engineers or taking ownership of a defined financial-core component

What we offer

• Competitive salary that recognises your talent and potential, including 13th salary (pro-rata)
• Performance-based bonus and equity participation in Tyme Group
• Full benefits and salary rank during probation
• Insurance coverage in accordance with Vietnamese labour law, plus premium health care for you and your family
• 20 days of leave annually: 15 annual leave, 3 sick leave, 1 birthday leave, and 1 Christmas leave
• Meal and parking allowances
• Hybrid working model with flexibility to work from home or the office
• 40-hour week Monday to Friday

About GoTymeX

GoTymeX is the engineering, product, and design organisation of the GoTyme Group, which builds digital banking products for customers in South Africa, the Philippines, and expansion markets across Asia and Africa. The team operates in a values-driven, international, agile culture.