Founding Senior Software Engineer (Backend)

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., * 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.

• 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., * 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:
• Practical Coding: Tackle real-world coding tasks with debugging in a basic environment set up like Python Flask or Node.js Express, etc.
• System Design: Architect a production-ready system.
• Tools & Automation: Build automations or improve workflows in any basic environment setup like Python Flask or Node.js Express, etc.

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/.