Senior Software Engineer II

Extend is revolutionizing the post-purchase experience for retailers and their customers by providing AI-driven solutions that enhance customer satisfaction and drive revenue growth. The Senior Software Engineer II will be responsible for building impactful software that influences how merchants manage customer fulfillment and servicing, collaborating with cross-functional teams to drive innovation and excellence.

Responsibilities:

• Tackle ambiguous, cross-system problems spanning all aspects of fulfillment and servicing — refunds, replacements, reverse logistics, and more
• Own large features end to end, from design through deployment, release, and monitoring
• Deliver scalable, event-driven, AI-native applications that elevate the customer experience
• Collaborate with platform teams to enhance overall system architecture
• Own the design, implementation, quality and safety of AI/agentic features in production systems
• Mentor other engineers across levels through code review, pairing, design collaboration and coaching
• Drive adoption of tooling and practices, including AI developer tooling, and codify the habits that make them effective
• Advocate for the proactive investments — refactors, observability, upgrades, technology adoption - that enable continuous improvement
• Communicate fluently across product, design, solutions, and ops to align outcomes with business goals

Requirements:

• 8+ years of full-stack experience
• Proven track record building distributed, highly available systems on AWS, with hands-on serverless experience
• Demonstrated experience shipping AI/LLM features to production
• Strong instincts for API design, versioning, idempotency, and backwards compatibility — especially where events drive money movement or fulfillment
• A track record of owning large, ambiguous, cross-system initiatives end to end
• Proven ability to influence beyond your team — aligning groups, distilling complex ideas for leadership, and pushing back with data
• A pattern of mentoring across levels and driving team-wide improvements that outlast any single project
• Strong data modeling and context engineering skills that ensure application quality and sound agentic decisioning
• Fluency with advanced AI developer tooling, a track record of using it to ship more, and a habit of bringing teammates along
• Exceptional communication across product, business stakeholders, designers, support, and engineers
• Expert in TypeScript, Node.js, and React