Senior Machine Learning Engineer [33222]

ABOUT THE COMPANY

The Company is using the first principles to reimagine the call center with cutting edge voice AI.

Since launching 18 months ago, thousands of companies now utilize Company’s AI voice agents to handle sales, support, and logistics calls that once required large teams of human agents. Backed by Y Combinator, Alt Capital, and other leading investors, we have scaled to $36M ARR with a team of 20 people, up from $5M at the start of 2025.

Our vision for 2026 is to build a modern CX platform where entire contact centers are powered by AI. Instead of basic automation that needs constant human tuning, we’re creating intelligent AI “workers” that can act as frontline agents, QA analysts, and managers — continuously executing, monitoring, and improving customer interactions.

We’re growing quickly and looking for ambitious builders who want to tackle hard technical problems, move fast, and have real impact at one of the fastest-growing voice AI startups.

Let’s build the future together.

• We’re a top 50 AI app in a16z list:
• #4 on Brex's Fast-Growing Software Vendors of 2025:
• We're also one of the top ranking startups on:

ABOUT THE ROL

EThis is a hands-on, high-ownership role for ML engineers who want to build production models that actually ship, and perform under real-world constraints. As a Founding Senior Machine Learning Engineer at The Company, you’ll work across the ML stack to power human-like voice agents that handle millions of real-time phone conversations

.You’ll fine-tune large language models and audio models, evaluate them with rigorous benchmarks (and human feedback), and deploy them into latency-sensitive, high-traffic systems. You’ll own model performance end-to-end—from training pipelines to post-deployment monitoring—and shape our ML strategy alongside the founding team

.If you’re excited by hard technical challenges, fast iteration, and the opportunity to define how voice AI works at scale, this role is a rare chance to do it from the ground up

.
KEY RESPONSIBILITI

• ESTrain & Tune Mode ls – Fine-tune LLMs and audio models to maximize speed, accuracy, and production-readiness—pushing the frontier of real-time AI voice experience
• s.Benchmark & Evalua te – Build datasets, define rigorous metrics, and measure model performance across high-impact voice AI tasks to guide developmen
• t.Deploy to Producti on – Work closely with engineering to ship models, monitor them in the wild, and ensure they stay fast, reliable, and accurate at scal
• e.Run Human Evaluatio ns – Build scalable pipelines to collect structured human feedback, benchmark subjective quality, and inform model iteration
• s.Level Up Infrastructu re – Design and maintain the ML infrastructure needed for fast experimentation, robust training, and continuous deploymen

t.YOU MIGHT THRIVE IF Y

• OUML Engineer with Real-World Experien ce – You’ve trained and shipped models in production. Bonus if you’ve worked with LLMs or audio model
• s.Fluent in Modern ML Sta ck – You know your way around Python, PyTorch, and today’s ML tools—from training pipelines to evaluation benchmark
• s.Execution-Orient ed – You move fast, take ownership, and focus on solving real problems over perfect one
• s.Startup-Rea dy – You’re adaptable, resilient, and energized by ambiguity and fast-changing prioritie
• s.Clear Communicator & Team Play er – You collaborate well across functions and push decisions forwar

d.JOB DETAI

• LSCash: $225,000 - $325,000 base sala
• ryEquity: Offers Equi
• tyLocation: Redwood City, CA,
• USUS Visas: The Company is open to sponsoring work authorization for qualified candidates, including H1B/H-1B, TN, L-1, E-3, F-1 (OPT/CPT), and O-1 visa

s.OTHER BENEFI

• TS100% covera ge for medical, dental, and vision insuran
• ce$70/day DoorDash cred it for unlimited breakfast, lunch, dinner, and snac
• ks$200/mon th wellness reimbursement (gym, fitness classes, etc
• .)$300/mon th commuter reimbursement (gas, Caltrain, etc
• .)$75/mon th phone bill reimburseme
• nt$50/mon th internet reimburseme

ntCOMPENSATION PHILOSOP

• HYBest Offer Upfront: Choose from three cash-equity balance options, no negotiation neede
• d.Top 1% Talent: Above-market pay (top 5 percentile) to attract high performer
• s.High Ownership: Small teams, >$1M revenue/employee, and significant equit
• y.Performance-Based: Offers tied to interview performance, not experience or past salarie