Founding Senior Software Engineer

Retell is building the new standard for automating call center communications, including sales, support, customer engagement, and retention calls. Backed by Altman Capital, Y Combinator, and top investors, we've raised a $4.7M seed round and hit $14M ARR in 15 months. Check us out on the Top Lean AI Native Companies Leaderboard at leanaileaderboard.com. About Retell AI At Retell AI, we're not just automating calls—we’re transforming how the world communicates. Our AI voice agents are reshaping sales, support, and customer engagement for leading brands. Backed by Alt Capital, Y Combinator, and top-tier investors, we've raised $4.7M in seed funding and hit $14M ARR with just 12 people. We’re one of the fastest-growing Voice AI startups and we're on a mission to become the standard for voice automation at scale. We're also one of the top ranking startups at https://leanaileaderboard.com/. About the Role As a Founding Senior Backend Engineer, you’ll shape the core systems powering millions of AI-driven conversations. You’ll tackle real-time audio, global telephony, and developer tooling, working across the stack with the founding team. This high-impact role offers rapid feedback loops, customer collaboration, and the chance to define a category-leading product. Key Responsibilities Build foundational architecture for Retell's platform, such as 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, driving delivery and monitoring. Collaborate with product and design teams to create intuitive APIs and interfaces for quick customer onboarding. Support customer onboarding, troubleshoot issues, and turn feedback into product improvements. You Might Thrive If You Have 2+ years of backend development experience with a degree in CS, CE, or EE. Take ownership like a founder, with a passion for impactful software. Thrive in fast-paced, ambiguous environments, solving new problems with curiosity. Communicate clearly, collaborate across teams, and drive momentum. Have startup experience or grit to adapt, with bonus points for cloud infra/DevOps knowledge. Job Details Job Type : Full-time, 70 hr/week (50 hr/week onsite with flexible hours + 20 hr/week work from home) Cash: 215k - 290k Equity : 0.25 - 0.45% Location : Redwood City, CA, US US Visas : Sponsors Visa & Green Card Other Benefits 100% medical, dental, vision insurance coverage Unlimited breakfast, lunch, dinner, and snacks Gym and daily commute fee reimbursement Internet and phone bills covered Compensation Philosophy Best Offer Upfront : Choose from three cash-equity balance options, no negotiation needed. Top 1% Talent : Above-market pay (top 5 percentile) to attract high performers. High Ownership: Small teams, >$1M revenue/employee, and significant equity. Performance-Based : Offers tied to interview performance, not experience or past salaries. Interview Process Online Assessment (25–30 min): One HackerRank coding questions on practical problem-solving (7 days to complete). Technical Phone Interview 1 (30 min): Live coding on CoderPad, focusing on data structures and algorithms. Technical Phone Interview 2 (30–45 min): Deeper CoderPad session on algorithmic thinking and coding fluency. Onsite/Virtual Interviews (2–3 hrs): Hosted in our office if located in the Bay Area or virtual, with three rounds: Learn More Retell AI - API That Turns Your LLM Into A Human-Like Voice Agent Retell AI Basics: Everything You Need to Start Building Voice Agents Join Retell AI to build the future of voice automation, shipping impactful code and defining a new standard for AI-driven communication.