Senior Software Engineer, W&B Agent - W&B

What You’ll Do:

ARIA is the AI Research and Iterations Agent that enables continuous experimentation at scale. The engineering team is responsible for building this research agent from scratch by leveraging  distributed backend systems that execute multi-turn agent conversations, to the React UI that thousands of ML practitioners interact with every day. Our mission is to ship a fast, reliable, and delightful agent experience that genuinely accelerates ML workflows, and every engineer on the team owns that outcome end to end.

About the role:

As a Senior Full Stack Engineer on the ARIA Agent team, you'll own features and systems across the entire stack — from backend infrastructure and API design to the React frontend that powers the chat interface, billing UI, and agent configuration experience. You'll build and maintain the distributed worker systems that run agent conversations at scale, design the streaming architecture that delivers real-time token output to the browser, and contribute to the frontend components that make ARIA feel fast and intuitive. You'll collaborate closely with ML science, product, iOS, and SRE teams — blending reliability engineering with product sensibility. Day to day, you'll move fluidly between debugging a production memory leak in a Kubernetes worker, shipping a new billing UI component, and hardening the egress controls on the code execution sandbox.

Who You Are:

• 4+ years of full stack engineering experience, with meaningful depth in both backend services and React/TypeScript frontend development.
• Strong Python backend skills — async patterns, FastAPI, distributed state machines, Kubernetes pod lifecycle.
• Proficient in TypeScript and React; comfortable building and maintaining production UI components including real-time streaming interfaces, complex state management, and responsive layouts across web and mobile web.
• Experience building and operating services at scale — rolling deploys, autoscaling, worker concurrency, graceful termination.
• Experience with observability tooling (Datadog, Weave tracing, structured logging) and a track record of building dashboards that surface actionable signals.
• Security-conscious engineering mindset — input validation, sandboxed code execution, egress controls, and payload hardening.
• Experience with MySQL or similar RDBMS for transactional state management.

Preferred:

• Experience building streaming UIs (server-sent events, WebSockets) with graceful fallback handling.
• Background in ML infrastructure, developer tooling, or observability platforms.
• Hands-on experience building and shipping production-grade AI agents — including tool use, multi-turn conversation management, and agentic reliability patterns.
• Comfortable thriving in a fast-paced startup environment — able to move quickly, make pragmatic tradeoffs, and iterate on real user feedback without sacrificing production quality.

Wondering if you’re a good fit? We believe in investing in our people, and value candidates who can bring their own diversified experiences to our teams – even if you aren't a 100% skill or experience match. Here are a few qualities we’ve found compatible with our team. If some of this describes you, we’d love to talk. 

• You love to turn messy, complex performance problems into clear, data-backed stories that lead to concrete action.
  
  
• You’re curious about how systems behave under real-world load and enjoy building experiments that reveal what’s really happening under the hood.
  
  
• You’re an expert in transforming deep technical insights into tools and processes that empower other engineers to build faster, more reliable systems.
  
  
• You find satisfaction in long-term, cross-team collaboration — helping others succeed by embedding performance thinking into their workflows.
  
  
• You get energy from bridging theory and practice: designing scalable architectures and writing the code that proves them out.
  
  
• You care deeply about measurement, iteration, and continuous improvement — not just fixing bottlenecks, but preventing them from ever recurring.
  
  

Why Us?

We work hard, have fun, and move fast! We’re in an exciting stage of hyper-growth that you will not want to miss out on. We’re not afraid of a little chaos, and we’re constantly learning. Our team cares deeply about how we build our product and how we work together, which is represented through our core values:

• Be Curious at Your Core
• Act Like an Owner
• Empower Employees
• Deliver Best-in-Class Client Experiences
• Achieve More Together

We support and encourage an entrepreneurial outlook and independent thinking. We foster an environment that encourages collaboration and provides the opportunity to develop innovative solutions to complex problems. As we get set for takeoff, the growth opportunities within the organization are constantly expanding. You will be surrounded by some of the best talent in the industry, who will want to learn from you, too. Come join us!

The base salary range for this role is $182,000 to $242,000. The starting salary will be determined based on job-related knowledge, skills, experience, and market location. We strive for both market alignment and internal equity when determining compensation. In addition to base salary, our total rewards package includes a discretionary bonus, equity awards, and a comprehensive benefits program (all based on eligibility).