Software Engineer, Character Platform & Tools

Sesame; San Francisco (CA); On-site; USD 120,000 - 160,000; Full time

Benefits offered by this job

Unlimited PTO

100% employer-paid health, vision, and dental

Flexible spending account with employer matching

Competitive stock options

Job summary

Sesame is seeking a Full-Stack Engineer to develop internal tools that enhance collaboration between engineers and creative professionals. You will work on the character research pipeline, transforming raw data into lifelike models through a React and Python-based platform.

Candidates should have over 4 years of experience in full-stack development, with a strong emphasis on UI/UX. The role offers a range of benefits, including health coverage for you and your dependents and a 401(k) match.

Qualifications

• 4+ years of experience building and shipping production full-stack systems.
• Experience in building internal platforms or tooling.
• Proficiency with modern web stacks, specifically React and Python.

Responsibilities

• Design and build internal tools for engineers and researchers.
• Create evaluation interfaces for model quality.
• Collaborate with teams to find automation opportunities.

Skills

Full-stack development

UI/UX design

Cloud infrastructure

Cross-disciplinary collaboration

Tools

React

Next.js

Python

FastAPI

GCP

Kubernetes

Job description

About Sesame

Sesame believes in a future where computers are lifelike - with the ability to see, hear, and collaborate with us in ways that feel natural and human. With this vision, we're designing a new kind of computer, focused on making voice agents part of our daily lives. Our team brings together founders from Oculus and Ubiquity6, alongside proven leaders from Meta, Google, and Apple, with deep expertise spanning hardware and software. Join us in shaping a future where computers truly come alive.

About the Role

The best platforms don't just support a workflow — they transform who can participate in it. At Sesame, we're building lifelike, compelling characters. That quality doesn't come from models alone. It comes from tight collaboration between engineers, ML researchers, and the creative professionals who define what a believable character is.

This is a full-stack engineering role focused on the internal tooling and platforms that power our character research pipeline. We're looking for engineers who are excited to build the systems that enable and accelerate that collaboration.

You'll architect and develop the internal platforms that take our team from raw data to fully-realized characters — evaluating quality and iterating cross-functionally through a React-based frontend atop a Python/FastAPI backend, backed by cloud ML infrastructure. The goal isn't just to support what we're doing today; it's to build a platform where our creative and research teams can experiment, iterate, and push the frontier of what's possible in character AI.

Responsibilities:

• Design and build internal tools that let engineers, researchers, and creative professionals experiment with and assemble configurations of models — importing datasets, running training jobs, evaluating outputs — without needing to write code for every workflow

• Build rich evaluation interfaces that surface model quality in ways that are readable and actionable for everyone, not just engineers

• Collaborate closely with ML researchers and creative teams to deeply understand their workflows, then find the automation opportunities that accelerate their work

• Take responsibility for the reliability and evolution of the tooling platform: monitoring, iterating on user feedback, and raising the ceiling of what's possible as the team's needs grow

• Contribute to ML infrastructure where it connects to tooling — you'll understand the pipeline well enough to know what to expose, what to abstract, and what to automate

Required Qualifications:

• Demonstrated 4+ years experience building and shipping production full-stack systems, with a strong sense of UI/UX for tools designed to be used by experts in other fields

• Experience building internal platforms or tooling, not just features — you think about the system, not just the ticket

• Proficiency with modern web stacks (we use React/Next.js and Python/FastAPI)

• Experience with cloud infrastructure (we're on GCP/Kubernetes)

• A strong sense of reliability and knowing when to build vs. borrow

• Curiosity about the domain: you don't need to be an ML engineer, but you should want to understand what you're building tools for

• Comfort working across disciplines — researchers, creative professionals, and operators — and translating between very different ways of thinking

Sesame is committed to a workplace where everyone feels valued, respected, and empowered. We welcome all qualified applicants, embracing diversity in race, gender, identity, orientation, ability, and more. We provide reasonable accommodations for applicants with disabilities. Contact [e-mail] for assistance.

Full-time Employee Benefits:

• 401 (k) max employer match: 3.5% of compensation

• 100% employer-paid health, vision, and dental benefits for you and your dependents

• Unlimited PTO and sick time

• Flexible spending account with employer matching up to $1,650/year (medical FSA)

• Guardian Employee Assistance Program (EAP)

• Opportunity to share in the company's success with competitive stock options

Benefits do not apply to contingent/contract workers.