Senior Payments Engineer Engineering London, UK

Ordernised; Greater London; Hybrid; GBP 80,000 - 110,000; Full time

Job summary

Ordernised in London is seeking a backend engineer to own payment, refund and reconciliation workflows where customer experience and financial correctness meet. You will design robust money-related systems and ensure traceability across services.

You will collaborate with product, operations and other engineers to implement reliable event processing, test for repeated events and support investigation through strong audit trails.

Qualifications

• Strong backend engineering experience in payment or financially sensitive workflows.
• Understanding of idempotency, retries, reconciliation and reliable event processing.
• Confident SQL and data modelling skills, including transactions and traceability.
• Ability to handle monetary calculations with consistent methods.
• Experience explaining complex failure modes to technical and non-technical colleagues.

Responsibilities

• Build and maintain payment-provider integrations for checkout, refunds and connected merchant accounts.
• Design idempotent webhook processing and explicit payment-state transitions.
• Develop reconciliation workflows that identify mismatches without altering financial records.
• Model monetary values, fees and rounding across interfaces and storage.
• Create tests for repeated events, partial failures, refunds and delayed confirmations.
• Improve audit trails and internal tools used to investigate payment issues.
• Coordinate payment releases and provider changes with engineering and operations teams.

Skills

Backend engineering

Payments systems

Idempotency

Retries

Reconciliation

SQL

Data modelling

Event processing

Auditability

Technical communication

Job description

Make payment, refund and reconciliation workflows understandable and dependable for restaurants and their customers.

You will own engineering work where customer experience and financial correctness meet. A payment event may arrive late, a webhook may be repeated and a refund may start in a different system, so clear state modelling and traceability are essential. You will partner with product, operations and other engineers to design robust money-related workflows and support effective investigation. This is a software role.

What you would be doing

• Build and maintain payment-provider integrations for checkout, refunds and connected merchant accounts.
• Design idempotent webhook processing and explicit payment-state transitions.
• Develop reconciliation workflows that identify mismatches without silently changing financial records.
• Model monetary values, fees and rounding consistently across interfaces and storage.
• Create tests for repeated events, partial failures, refunds and delayed confirmations.
• Improve audit trails and internal tools used to investigate payment issues.
• Coordinate payment releases and provider changes with relevant engineering and operational teams.

What we are looking for

• Strong backend engineering experience on payment or other financially sensitive workflows.
• Understanding of idempotency, retries, reconciliation and reliable event processing.
• Confident SQL and data-modelling skills, including transactions and traceability.
• Ability to handle monetary calculations consistently without unsafe floating-point assumptions.
• Experience explaining complex failure modes to technical and non-technical colleagues.

Useful, but not essential

• Hands-on Stripe or Stripe Connect experience.
• Experience with multi-merchant commerce platforms.
• Familiarity with payment-security practices and minimising sensitive data exposure.