Applied AI Engineer (Customer Facing)

About this role

ABOUT RETELL AI Retell AI is using first-principles thinking to reimagine the call center with cutting-edge voice AI. Thousands of companies now use Retell'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've scaled to $80M in ARR with a team of 50, up from $5M at the start of 2025, and are now valued at over $1.5B. 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 act as frontline agents, QA analysts, and managers, continuously executing, monitoring, and improving every customer interaction. We're growing fast and looking for ambitious builders who want to tackle hard technical problems, move quickly, and have a real impact on one of the fastest-growing voice AI companies in the world. Let's build the future together. RECENT RECOGNITION: - No. 1 Best Places to Work in the Bay Area, San Francisco Business Times 2026 https://finance.yahoo.com/technology/ai/articles/voice-ai-startup-retell-ai-145200025.html - Top 50 AI Apps, a16z (2025) https://a16z.com/the-ai-application-spending-report-where-startup-dollars-really-go/ - #3 Fastest-Growing Software Company, G2 Best Software Awards 2026 https://company.g2.com/news/g2s-2026-best-software-awards - Best Agentic AI Software, G2 Best Software Awards 2026 https://www.retellai.com/blog/retell-ai-recognized-as-the-best-agentic-ai-software-by-g2 - #4 Fastest-Growing Software Vendor, Brex Benchmark 2025 https://www.brex.com/journal/brex-benchmark-december-2025 - Enterprise Tech 30 Class of 2026, Nasdaq & Wing VC https://www.nasdaq.com/videos/retell-ai - Top-Ranked Startup, Lean AI Leaderboard https://leanaileaderboard.com/ - Backed by Y Combinator https://www.ycombinator.com/companies/retell-ai   ABOUT THE ROLE Retell AI is transforming customer experience with Voice AI for enterprises, including customers like CVS/Aetna, American Airlines, Lenovo, and Grab. We're building the infrastructure that powers millions of AI-powered phone conversations every month—and we're just getting started. We're hiring an Applied AI Engineer to work directly with enterprise customers to design, build, and deploy production AI voice applications. As an Applied AI Engineer, you'll sit at the intersection of AI, software engineering, and customer success. You'll partner closely with customer engineering teams to integrate Retell into their products, solve complex technical challenges, optimize AI workflows, and help customers successfully launch and scale Voice AI in production. This is an ideal role for someone who enjoys building software, solving ambiguous technical problems, and working directly with customers. You'll collaborate daily with Engineering, Product, and Customer Success while helping shape the future of enterprise AI. This is a full-time position based in our Redwood City headquarters. WHAT YOU'LL DO BUILD AI SOLUTIONS WITH CUSTOMERS - Design, build, and deploy production AI voice applications. - Partner with customer engineering teams to integrate Retell APIs and SDKs. - Develop custom workflows, automations, and conversational AI experiences. - Help customers architect scalable AI systems for production. SOLVE COMPLEX TECHNICAL PROBLEMS - Debug production issues across APIs, webhooks, telephony, SIP, authentication, latency, and infrastructure. - Investigate AI behavior and improve prompt quality, reliability, and performance. - Work directly in customer codebases when needed. - Own technical implementation from proof of concept through production launch. DRIVE CUSTOMER SUCCESS - Lead technical onboarding for enterprise customers. - Serve as the primary technical advisor during implementation. - Guide customers on AI best practices, architecture, and deployment strategies. - Help customers expand into new AI use cases across their organizations. INFLUENCE THE PRODUCT - Partner closely with Product and Engineering to improve the platform. - Turn customer feedback into product improvements. - Identify recurring customer pain points and propose scalable solutions. - Help define best practices for deploying enterprise Voice AI. WHAT WE'RE LOOKING FOR MUST HAVE - Bachelor's degree in Computer Science, Computer Engineering, Electrical Engineering, or a related technical field. - 2+ years of software engineering or customer-facing technical experience building and deploying production applications. - Strong programming skills in Python, TypeScript, or similar languages. - Experience working with APIs, SDKs, and distributed systems. - Excellent debugging and problem-solving skills. - Strong communication skills and the ability to work directly with technical customers. - Available to work standard U.S. business hours with overlap with our Pacific Time team and enterprise customers. NICE TO HAVE - Experience building AI or LLM-powered applications. - Experience with Voice AI, speech technologies, or conversational AI. - Experience with cloud infrastructure (AWS, GCP, Azure). - Experience with telephony, SIP, Twilio, or real-time communications. - Startup experience. - Customer-facing engineering, solutions engineering, or consulting experience. - Willingness to travel up to 10% for customer workshops, launches, and onsite engagements. YOU MIGHT THRIVE IF - You enjoy building software that solves real customer problems. - You like working directly with engineers and technical stakeholders. - You enjoy owning projects from architecture through deployment. - You're excited about AI and love experimenting with the latest models and technologies. - You thrive in fast-moving startup environments with lots of ownership. - You enjoy weari