Senior Backend Engineer (AI Agent)

Welcome to the Agentic Commerce Era At Commerce, our mission is to empower businesses to innovate, grow, and thrive with our open, AI-driven commerce ecosystem. As the parent company of BigCommerce, Feedonomics, and Makeswift, we connect the tools and systems that power growth, enabling businesses to unlock the full potential of their data, deliver seamless and personalized experiences across every channel, and adapt swiftly to an ever-changing market. We believe in harnessing AI responsibly to unlock new possibilities, and we’re looking for individuals who use it intentionally to solve problems, accelerate outcomes, and expand what’s possible in their role. Our purpose is to help businesses confidently solve complex commerce challenges so they can build smarter, adapt faster, and grow on their own terms. If you want to be part of a team of bold builders, sharp thinkers, and technical trailblazers who shape the future of commerce, this is the place for you. BigCommerce is building a new team to deliver a suite of conversational AI agents spanning the B2B commerce lifecycle — Product Discovery, Pricing & Quoting, Order Automation, Fulfillment & Delivery, and Post-Sale Support. The agents are built in Go on Google ADK with Gemini, with evaluation infrastructure in Braintrust and a streaming AG-UI frontend. As a Senior Backend Engineer specializing in AI agents, you will design the agents themselves: orchestration, sub-agent architecture, tool integration, prompt engineering, and — critically — the evaluation discipline that determines whether these agents are trustworthy enough to ship. Agent quality in this domain is won on evals, not just code, and you will own that practice for

the team. BigCommerce, part of the Commerce brand family, helps merchants increase sales at every stage of their growth. From small startups to mid-market businesses and large enterprises, we provide the leading e-commerce platform. Our customers can then concentrate on what's most important: growing their businesses. We enable our customers to build, innovate, and grow, collectively reshaping the e-commerce industry. What You’ll Do Design, build, and iterate on AI agents in Go/Python using an orchestrator/sub-agent architecture, covering intent interpretation, delegation, and safe action execution Own eval-driven development: build and maintain golden datasets, scorers, and regression suites (Braintrust or similar) for critical quality metrics such as discovery recall and quote accuracy Develop and refine prompts, model configurations; treat prompts and model settings as versioned, tested artifacts Integrate agents with MCP servers and backend tools, defining safe tool-call contracts, approval flows for write actions, and guardrails against prompt injection and abuse Instrument agents with tracing, metrics, and cost tracking; use production signals to drive quality improvements Collaborate with product designers and frontend engineers to deliver intuitive, useful conversational experiences Quickly build proof-of-concept agents to validate user stories, then harden them to GA quality Drive architecture decisions on ambiguous problems and mentor other engineers in agent engineering practices Who Are You 5+ years of experience in backend or full-stack software development, with hands-on experience building agentic AI/LLM applications Education: Preferred minimum Bachelor's degree in CS, EE, SW, CE, MIS; or equivalent experience Strong and proven development skills in any major language (Go/Python/Ruby/PHP) Experience working with LLMs (Gemini, Anthropic, OpenAI, etc.) in production systems Experience with LLM evaluation: building datasets, defining scorers/metrics, and using eval results to drive iteration Strong understanding of prompt engineering, tool/function calling, and agent orchestration patterns Deep experience designing and building APIs (gRPC, GraphQL, REST) and integrating data across systems Hands-on experience building MCP servers or LLM tool integrations Excellent problem-solving skills and ability to work in a fast-paced, exploratory environment Strong collaboration and communication skills in cross-functional teams Strong preference toward execution and delivery Preferred: Experience with agent frameworks (Google ADK, LangChain/LangGraph, Semantic Kernel, or similar) Experience with evaluation/observability platforms (Braintrust, LangSmith, or similar) Experience with RAG systems and retrieval quality tuning Experience with e-commerce platforms or SaaS product development Background in conversational AI or natural language processing Work Where You Thrive For candidates based in the Austin or Atlanta metro area, the position follows a hybrid work model with three days per week in the office, balancing focused individual work with meaningful in-person collaboration. #LI-REMOTE #LI-GC1 (Pay Transparency Range: $116,000.00 - $195,000.00)