Senior Fullstack Engineer

About the role

MEET SIENA

Siena is the Agent of Record for CX, built for consumer brands like Spanx, FIGS, Brooklinen, and Grüns.

It runs as a connected multi-agent stack on top of a shared intelligence layer: agents that sell, support, listen, handle social and voice across the entire customer journey, turning every conversation into signal you can act on.

THE TEAM

We are a small, fully distributed, global team. We have built leverage into how we work, which is what lets a team this size move at the speed we do.

We hire athletes. Everyone here owns real outcomes, defaults to writing over meetings, communicates with directness, and acts the moment they see something worth acting on. Low ego, high standards, fast clock.

If you want to set the bar rather than follow one, keep reading.

THE ROLE

You'll own meaningful parts of the platform end to end, taking ambiguous problems and shipping reliable, high-performance systems that real brands depend on daily. You'll work closely with product to shape scope, make real architectural calls in your area, and do your best work without being managed task by task. This is for engineers who want ownership and can carry it.

WHAT YOU'LL DO

- Own features and systems across the full stack (frontend, backend, infrastructure) from problem definition through production.

- Partner with product to break down ambiguous scope and ship in iterative, high-impact releases.

- Make real architectural and design decisions in your area, and explain the reasoning so the team can build on it.

- Take cutting-edge language models into enterprise customer workflows, where reliability and safety actually matter.

- Solve hard engineering problems: API performance, microservices, scaling across channels and brands.

- Maintain and improve our AWS infrastructure with a DevOps mindset.

- Raise the bar around you. Share what you know, review thoughtfully, help teammates level up.

WHO YOU ARE

The Bar: if you're missing any of these, this isn't the role for you

- 5+ years shipping and owning systems that are live in production, not personal projects.

- Strong in our core stack: Node.js, React, TypeScript, Express.

- You've shipped LLM-powered features to real users. This is a must, not a bonus. You know what breaks when models meet production traffic.

Strong Signal: not dealbreakers, but what separates a good hire from a great one

- Solid with AWS (Fargate, Lambda, EC2, SQS), PostgreSQL, and Redis.

- Comfortable with CI/CD pipelines (CodePipeline, GitHub Actions, or similar).

- Experienced with microservices and scalable systems.

- Product-focused. You think past the code to customer outcomes and business impact.

- High-ownership and direct. You fix problems without waiting to be told.