Senior Backend Engineer; AI Agent

About the Role

Big Commerce 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 the evaluation discipline that determines whether these agents are trustworthy enough to ship.

• 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.

• 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 evaluation 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.

• Experience with agent frameworks (Google ADK, Lang Chain/Lang Graph, Semantic Kernel, or similar).
• Experience with evaluation/observability platforms (Braintrust, Lang Smith, 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.

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.

Pay Transparency Range: $ – $. Final compensation will be determined based on relevant experience, skills, qualifications, geographic location, and internal equity.

At Commerce, we believe that celebrating the unique histories, perspectives and abilities of every employee makes a difference for our company, our customers and our community. We are an equal opportunity employer and the inclusive atmosphere we build together will make room for every person to contribute, grow and thrive.