Java Backend- Fiserv / CardPointe (ISV) Payments & Merchant Onboarding Integration

1) About the Project We are building a modern SaaS platform for service-based businesses. One core piece is our payments layer: we are integrating with Fiserv / CardPointe (as an ISV partner) to onboard our business customers onto card processing and to run card transactions on their behalf. We need a backend engineer with real, hands-on Fiserv/CardConnect integration experience to own this work. We use AI-assisted development (primarily Claude Code) to accelerate both frontend and backend work. 2) About the Role Most of the development is done using AI tools, mainly Claude Code. Your role is to guide the AI, review the generated code, provide feedback, and refine the backend integration to production standards. This role is ~90% backend and focused specifically on the Fiserv/ISV payments and merchant-onboarding integration. This position is ideal for a Java backend engineer who has actually shipped a Fiserv/CardPointe (CardConnect) integration before and understands both the merchant-boarding side (CoPilot Partner API) and the transaction side (CardPointe Gateway), including the PCI and sensitive-data handling that comes with them. Key requirement: direct, hands-on Fiserv / CardConnect / CardPointe integration experience. General "payments experience" is not enough — applicants must name the specific Fiserv products/APIs they have shipped. 3) Key Responsibilities Design and build robust Spring Boot 3.x backend services using Java 21/25 Integrate the Fiserv CardPointe CoPilot Partner API for white-label merchant onboarding/boarding (application submission, document upload, equipment orders, application status tracking, MID issuance) Integrate the CardPointe Gateway API for card-not-present transactions (Hosted iFrame Tokenizer, authorize/capture/refund) and consume settlement/funding reporting endpoints Model and persist merchant-application data with correct multi-tenant isolation and secure handling of sensitive PII (owner identity, tax IDs, bank/ABA routing, uploaded documents) Build clean internal REST contracts and events so downstream services can consume a boarded merchant's MID Implement resilient integration patterns: idempotent submits, status polling/webhooks, retries, and honest error/state handling against a third-party processor Keep card data out of scope where possible (Fiserv-hosted tokenization) and keep the PCI boundary clean Write clean, well-tested, production-ready code and clear integration documentation 4) Requirements Strong Java + Spring Boot experience (4+ years) Direct, hands-on integration experience with Fiserv / CardConnect / CardPointe — the key requirement; please cite the specific integration in your application Experience integrating merchant onboarding / boarding APIs and/or payment gateway APIs in production Solid understanding of payment concepts: MIDs, tokenization, authorization vs. settlement vs. funding, card-present vs. card-not-present Awareness of PCI-DSS scope, PCI-safe tokenization patterns, and secure handling of PII (SSN/EIN, bank/ABA) Strong experience with RESTful third-party API integration, including auth (bearer tokens / credential-based), retries, idempotency, and webhook or polling status models Comfortable working against sandbox/UAT environments and secrets stored in a secrets manager (never in code) Strong problem-solving and clean, well-tested code practices Proven ability to work effectively with the Claude Code agent as a coding assistant — this is central to how we build, not optional. You must be able to direct Claude Code with clear prompts, review and correct what it produces, break work into steps it can execute well, and steer it to production-quality results. General "AI tool" familiarity is not the same as knowing how to get good output from Claude Code specifically. Good English communication skills 5) Nice-to-Haves Prior work as or with a Fiserv/CardConnect ISV partner (CoPilot / partner-portal onboarding) Experience with CardPointe Integrated Terminal (CIT) / Clover / Ingenico card-present devices Residual / portfolio / merchant-reporting integrations Background in fintech, payments processing, or merchant acquiring Multi-tenant SaaS and Postgres (row-level security) experience 6) Contract Details Long-term/ongoing project (more than 6 months) Hourly contract Work from home, but developers will remote login (via secure VPN + company-managed access) into a US-based development computer for all work Flexible working hours We will start with a small unpaid test task to evaluate the collaboration before moving forward with a longer-term contract. If you are a Java backend engineer who has actually integrated Fiserv/CardPointe and enjoys building production-grade payment systems using modern tools and AI assistants, we would love to hear from you! Please apply with relevant project links (especially any Fiserv/CardConnect/CardPointe or payment-gateway integration work), a short note on exactly which Fiserv APIs you have used, and your expected hourly rate.