Hauler Hero Inc. - Senior Backend Engineer, Payments
Requirements
• 5+ years building production backend systems • 2+ years building or operating payment systems in production, including card processing, recurring billing, refunds and reversals, or reconciliation • Direct experience integrating with at least one payment processor or gateway API • Experience designing and operating systems with distributed data and meaningful scale • Experience working in Agile/Scrum environments, with strong Git/GitHub workflow experience • Core Technologies • Strong proficiency with Spring Boot (Java and/or Kotlin) and willingness to write Kotlin as your primary language • Spring Boot (Java and/or Kotlin) • Deep experience with relational databases, especially PostgreSQL • Experience building and maintaining production APIs • Payments • Working knowledge of idempotency, at-least-once vs. exactly-once processing, retries, and reconciliation patterns for money movement • Understanding of PCI DSS scope and tokenization; you know what must never touch our servers • Experience with financial edge cases, including partial refunds, voids vs. reversals, chargebacks, declined and stuck transactions, and timezone-sensitive scheduling • Ability to translate product requirements into technical solutions • Strong problem-decomposition and debugging skills, including production incident work • Solid computer science fundamentals and engineering judgment • Clear written and verbal communication skills • Integrations with payment processors • Ledger design or double-entry accounting concepts; invoicing and accounts-receivable systems • Event-driven architectures such as Pub/Sub or Kafka • Google Cloud Platform, including GKE, Cloud Run, and Cloud SQL, and Redis • Background in fintech, B2B SaaS, or logistics • Backend: Kotlin, Java, Spring Boot, PostgreSQL • Backend: • Payments: Multiple card processors behind an in-house connector layer; Redis for idempotency and reconciliation • Payments: • Cloud: Google Cloud Platform (GKE, Cloud Run, Cloud SQL) • Cloud: • Caching: Redis, Firestore • Caching: • Frontend: React • Frontend: • CI/CD: Cloud Build, GitHub Actions • CI/CD: • Monitoring: New Relic, Google Operations • Monitoring: • What We Look For • Ownership & Judgment • You take problems through to resolution • You balance pragmatism with quality, and in payments you know quality wins • You identify and eliminate single points of failure, both in systems and in knowledge • Communication • Clear, proactive written communication • Willingness to surface risks and tradeoffs early • Calm and precise during incidents; you document what happened and what changes • Mindset • Curious, growth-oriented, and adaptable • Comfortable with ambiguity and iteration • Willing to refactor continuously as systems evolve
Responsibilities
• Payments Platform • Design, build, and operate the services behind card processing, refunds, and payment reconciliation • Own our processor integrations behind a common connector layer, including onboarding new processors and retiring old ones • Make the payment pipeline safe by construction through idempotent charge paths, processor timeouts and retries outside database transactions, webhook handling, and an automated reconciler that catches stuck or mismatched payments • Build audit trails so every payment and refund is traceable • Be a first responder for payments incidents and drive root cause analysis and structural fixes, not one-off scripts • Partner with Customer Success on the payments support queue and turn recurring tickets into product fixes • Core Backend Development • Write clean, testable, high-performance code in Kotlin and Java using Spring Boot; new backend code is written in Kotlin • Kotlin and Java using Spring Boot • Design and implement APIs that scale with real production workloads • Refactor and extend existing services to improve reliability and maintainability • Data & Performance • Design and optimize relational schemas in PostgreSQL • Write and tune performant SQL for large data volumes and validate that access patterns scale under load • Collaboration & Delivery • Work as part of a cross-functional Agile/Scrum team and participate in design reviews, code reviews, and architectural discussions • Collaborate with product, frontend, and Customer Success on billing and payments features • Mentor engineers through code reviews and proactively share context to avoid knowledge silos
Benefits
• Health, dental, vision insurance • Remote-first culture • Modern development tools and AI assistants
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