Sr Founding Backend Engineer

Senior Backend Engineer Voice AI Startup

About the Company

Our client is a fast-growing Y Combinator-backed Voice AI startup transforming sales, support, and customer engagement. With $5M in seed funding and approaching $30M ARR already, achieved with just 20 people, they're building the standard for voice automation at scale.

The Role

As a Founding Senior Backend Engineer, you'll build the core systems powering millions of AI-driven conversations. You'll work on real-time audio, global telephony, and developer tooling, collaborating directly with the founding team to define a category-leading product.

Key Responsibilities

Build foundational architecture including prompt orchestration, testing frameworks, observability dashboards, and telephony integrations

Design scalable backend systems and DevOps workflows for reliable performance across millions of calls

Lead complex projects from architecture to production, owning delivery and monitoring

Collaborate with product and design teams to create intuitive APIs for rapid customer onboarding

Support customer onboarding, troubleshoot issues, and translate feedback into product improvements Requirements

2+ years backend development experience

CS, CE, or EE degree or equivalent practical experience

Ownership mindset with passion for impactful software

Thrives in fast-paced, ambiguous environments with strong problem-solving skills

Clear communication and cross-functional collaboration abilities

Bonus: Startup experience and cloud infrastructure/DevOps knowledge Compensation & Benefits

Salary: $200K - $280K

Equity: 0.25% - 0.45%

Schedule: Full-time, 70 hrs/week (50 onsite + 20 remote, flexible hours)

Location: Redwood City, CA

100% medical, dental, vision coverage

Unlimited meals and snacks

Gym and commute reimbursement

Visa sponsorship available (H1B, TN, L-1, E-3, F-1, O-1)

Interview Process

Online coding assessment (25-30 min)

Technical phone interviews (2 rounds focusing on data structures and algorithms)

Onsite/virtual interviews: practical coding, system design, and automation