Senior Software Engineer II, Customer Experience

About this role

Kard is building commerce media infrastructure that connects financial institutions, financial-services platforms, and merchants through data and merchant-funded rewards. As our reach expands, we are building for a step-change in scale, and for opportunities ranging from more relevant rewards and marketer intelligence to new commerce and distribution models. About the Role The Customer Experience (CX) team owns the systems that power Kard’s end-to-end rewards experience: transaction matching and the cellar pipeline, offer ingestion and delivery (including partner integrations like Rewards Network and SEATED), the cell-based routing architecture, and the Support API that keeps our internal and partner-facing tooling running. As a Senior Software Engineer II, you’ll operate at the center of this — designing and building the services that ingest, match, and settle transactions at scale, while helping the team raise its bar on operational readiness, testing, and documentation. This role reports into the CX engineering team, with a strong focus on our issuer and partner-facing surface area, working alongside Support, Design, and Product through Kard’s Shape Up-based pitch cycle. You’ll drive pitches end-to-end, participate in on-call, and help the team keep pace with a fast-growing transaction volume and issuer surface. Responsibilities Architect and build scalable services across transaction matching, the cellar pipeline, and offer ingestion — new work defaults to Go and Postgres; existing services are a mix of TypeScript and MongoDB. Own features end-to-end through Kard’s Shape Up cycle: discovery, pitch writing, implementation, testing, and production rollout, including a written launch/rollback plan for anything touching transaction or offer data. Actively participate in on-call, incident response, and IOC (interrupt/on-call) triage; drive root-cause fixes rather than one-off patches (e.g., ingestion validation gaps, UID/timestamp mismatches, Datadog alert coverage). Strengthen our issuer/client-facing APIs and SDKs — reliability, clarity, and self-service — so partners and Support can resolve more issues independently, reducing engineering escalations. Lead by example: make decisive technical calls and foster collaboration across Product, Design, and Engineering to keep the team moving toward CX’s strategic goals. Champion enhancements to our tech stack, methodologies, and standards — authentication, rate limiting, deployment, observability, error handling, and test coverage (unit, integration, end-to-end) — with an eye toward resilience, agility, and quality, not just shipping speed. Mentor engineers, contribute to design and architecture discussions, and help the team consolidate or deprecate legacy/overlapping services rather than letting them accumulate. Write clear documentation and playbooks (local dev setup, deployment, troubleshooting) so ownership doesn’t stay concentrated with one or two people. Desired Skills Expert programming skills in Go and/or TypeScript, with experience building scalable, secure, high-performance backend services. Solid experience with distributed systems, event-driven architectures (SQS, Temporal), and both relational and document databases (Postgres and MongoDB). Proficiency with AWS and Infrastructure-as-Code (Terraform), including container technologies (Kubernetes/EKS) and serverless components (Lambda). Experience working on transaction-processing, matching, or ingestion pipelines where correctness and idempotency matter. Comfort leading a technical project from discovery through production rollout, including writing clear specs and driving cross-team collaboration (e.g., with Support, Data, or partner integration teams). Skilled with agentic software development — using AI tools (e.g., Claude Code, Codex) to plan and implement complex features, not just autocomplete — while still owning the design and quality of the result. Commitment to fostering an inclusive, collaborative engineering