Senior Adyen Software Engineer (remote)

Job Title: Senior Adyen Engineer
Role Type: Contract
Role Duration: 9+ months contract – good chance to extend
Work Model: REMOTE 

Role Overview
Our client is a digital agency specializing in digital transformation for established enterprises and growth-stage companies. This client builds complex, deeply integrated applications that power critical experiences for enterprises and startups alike. Engineering teams work across web, mobile, and cloud platforms, delivering solutions that range from multi-million-dollar platform modernizations to fast-moving, high-impact digital builds.

We’re seeking a Senior Adyen Engineer to serve as an embedded payment subject matter expert on a complex, enterprise-scale PSP migration engagement. The client is a large North American telecommunications provider migrating from a legacy payment infrastructure to Adyen’s platform across a multi-brand, multi-LOB environment.

This is a consultative and advisory engagement. The client''s internal engineering teams retain ownership of all hands-on development. The Senior Adyen Engineer will provide expert guidance, architectural review, integration design support, configuration validation, and risk identification throughout the migration lifecycle, working in close coordination with a primary System Integrator and the client''s program leadership. The engagement covers a phased migration affecting 40+ downstream systems, multiple billing platforms, fraud and tokenization infrastructure, and a parallel coexistence period with a legacy PSP. The right candidate brings both depth in Adyen''s platform and the credibility to advise enterprise engineering teams at a senior level.

Core Responsibilities
Adyen Platform Advisory

• Guide engineering teams on Adyen Checkout API, tokenization, webhooks, dispute management, and multi-merchant account structures.
• Translate Adyen platform capabilities, constraints, and best practices into actionable implementation guidance for client developers.
• Review and validate integration architecture decisions, surfacing gaps, anti-patterns, and risks before they reach production.

• Advise on phased migration from legacy token repository to Adyen''s token vault, including re-tokenization strategy and PAN retrieval options.

• Guide PCI scope management during migration windows and coexistence-period design for parallel legacy PSP / Adyen operation.
• Support segmentation model definition (allow/deny lists, friendly-user groups, LOB rollout sequencing).

• Review and advise on Adyen Checkout API, webhook event processing, multi-brand merchant hierarchy, and downstream billing system integration impacts.

• Assist in designing federated micro-frontend integration with Adyen Drop-In or custom hosted components.
• Review API and back-end abstraction patterns for the Payment Services layer, including token flows, 3DS metadata, fraud signals, and refund/chargeback handling.
• Support Pay-By-Link design, IVR payment capture patterns, and OTCC/PACC flow validation.
• Review front-end, back-end, PSP alignment across all lines of business and channels.

• Advise on the architectural shift from batch-close/next-day settlement to Adyen''s configurable sales-day payout model with inline fee deduction.

• Help the client design reconciliation processes, reporting pipelines, and billing system adaptations required by this model change.
• Support coexistence-period reconciliation design and mixed-state routing validation.

• Provide guidance on Adyen merchant hierarchy setup and merchant account structure for multi-brand environments.

• Advise on sandbox, pilot, and production environment promotion strategy.
• Support Adyen Customer Area configuration, WIAM/SSO integration, and RBAC structure for client internal teams.

• Serve as the technical bridge between the client, SI teams, and Adyen''s technical resources.
• Clarify requirements, validate API versioning, confirm webhook configuration, and manage integration backlog alignment between program teams and Adyen.

• Support the client in engaging Adyen on escalations, environment issues, and roadmap considerations.

• Proactively surface Adyen-specific risks and integration complexities, including:
  • 3DS configuration and step-up authentication impacts on customer experience
  • Fraud rule migration and tuning during the coexistence period
  • Canadian payment method considerations (Interac, Visa Debit flows)
  • Webhook reliability, idempotency, and retry edge cases
  • PCI boundary impacts of token vault migration
• Prepare concise risk documentation and recommendations for program leadership and steering committees.

• Support the QA team with Adyen-specific test scenario design, including OTCC, tokenization, 3DS, dispute, and Pay-By-Link flows.

• Advise on sandbox environment configuration and production readiness criteria for payment flows.
• Assist with migration-specific test plans and mixed-state (legacy + PSP) regression scenarios.

• 7+ years of professional software engineering experience with a strong focus on payment systems and PSP integrations.

• 3+ years of direct, hands-on Adyen implementation experience in production environments — not just advisory exposure.
• Demonstrable experience with Adyen Balance Platform, Checkout API, tokenization, webhooks, and dispute management in enterprise-scale deployments.
• Experience advising or supporting large internal engineering teams in a consultative capacity (not required to be the only one writing code).
• Background in complex, phased migration programs — preferably involving PSP transitions, token vault migrations, or payment infrastructure modernization.
• Experience with multi-brand or multi-merchant account structures on Adyen.

• Adyen Checkout API: Drop-In, Components, Custom UI, session-based and tokenized flows.
• Adyen Balance Platform: sub-merchant onboarding, balance accounts, fund flows.
• Tokenization: network tokens, stored credentials, PAN retrieval, vault architecture.
• Webhooks: event-driven architecture, idempotency, retry design, HMAC validation.
• 3DS2: challenge flows, exemptions, frictionless configuration.
• Dispute management: chargeback flows, retrieval requests, evidence handling via API.
• Adyen Customer Area: merchant hierarchy, WIAM/SSO, RBAC, reporting, notifications.
• Settlement & reconciliation: Adyen sales-day payout model, fee deduction, settlement reports.

• Strong back-end development background; language-agnostic but able to read and review code across common enterprise stacks (Java, Python, Node.js, .NET).

• Event-driven architecture and asynchronous messaging patterns (Kafka, SQS/SNS, or equivalent).
• REST API design principles, API versioning, contract governance.
• PCI DSS fundamentals: scope reduction, SAQ-A alignment, secure data handling, audit evidence.
• Cloud platform experience (AWS preferred) — familiarity with API Gateway, Lambda/ECS, SQS, CloudWatch.
• Familiarity with observability tooling for payment flows (Datadog, Splunk, or equivalent).

• Able to communicate complex payment and PSP concepts clearly to both technical engineers and non-technical business stakeholders.
• Comfortable operating in a client-facing advisory role where influence, not authority, is the primary lever.
• Experience working in multi-vendor delivery environments with clear governance structures.

• Prior experience in telecommunications, utilities, or other high-volume recurring billing environments.
• Familiarity with Canadian payment market specifics (Visa Debit, Interac network behavior, Canadian acquiring nuances).

• Experience with IVR payment capture patterns and call-center agent-assisted payment flows.
• Exposure to micro-frontend architectures and federated payment UI component integration.
• Experience with Adyen''s fraud module (RevenueProtect) - rule design, risk scoring, and migration of rule sets across PSPs.
• Formal PCI DSS or payment security training/certification (e.g., PCIP, ISA).
• Prior engagement experience as a payment SME or payment architect on a large SI program.

System One, and its subsidiaries including Joulé and Mountain Ltd., are leaders in delivering outsourced services and workforce solutions across North America. We help clients get work done more efficiently and economically, without compromising quality. System One not only serves as a valued partner for our clients, but we offer eligible employees health and welfare benefits coverage options including medical, dental, vision, spending accounts, life insurance, voluntary plans, as well as participation in a 401(k) plan.

System One is an Equal Opportunity Employer. All qualified applicants will receive consideration for employment without regard to race, color, religion, sex (including pregnancy, childbirth, or related medical conditions), sexual orientation, gender identity, age, national origin, disability, family care or medical leave status, genetic information, veteran status, marital status, or any other characteristic protected by applicable federal, state, or local law.

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