
Retell is the #1 voice AI agent platform, enabling you to build, test, deploy, and monitor voice AI agents. Industries such as healthcare, insurance, financial services, and logistics use Retell to automate and enhance call operations.

Retell is the #1 voice AI agent platform, enabling you to build, test, deploy, and monitor voice AI agents. Industries such as healthcare, insurance, financial services, and logistics use Retell to automate and enhance call operations.
What they do: Voice-first conversational AI platform to build, deploy, and monitor AI voice agents that automate inbound and outbound phone calls.
Stage & funding: Seed-stage; $4.6M seed round (lead: Alt Capital).
Founding & HQ: Founded 2023; co-founder & CEO Bin Wu; based in San Francisco, CA.
Enterprise features: Telephony integrations (SIP trunking), low-latency LLM + speech models, and enterprise compliance claims (HIPAA, SOC 2 Type II, GDPR).
| Company |
|---|
Call center and phone-based customer workflows (inbound/outbound calls, customer service, appointment scheduling, call operations automation).
2023
Technology, Information and Internet
$4.6M
Round included participation from Y Combinator, Carya Venture Partners, and 20+ founders/executives/operators; named participants include Jack Altman, Aaron Levie, Siqi Chen, Michael Seibel, and Peer Richelsen.
โSeed round led by Alt Capital with participation from Y Combinator, Carya Venture Partners, and multiple founders/executives (including named angels and operators).โ
About Retell Ai Retell AI 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 Retellโs 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.
In 2026, We are expanding our vision to build a CX platform of the AI era where the entire contact center is reimagined as a team of AI employees. We are moving beyond mechanical automation that relies on human finetuning to instead transform core functions into intelligent, opinionated AI roles. Frontline agents, QA analysts, and managers now operate as distinct digital workers that serve as the new interface for customer experience. They execute, monitor, and improve continuously to create a system where software behaves like an organization.
Weโre scaling fast, and weโre looking for bold, ambitious people to help us build the gold standard for voice automation. If you want to work on deeply technical challenges, move fast, and make an outsized impact at one of the fastest-growing Voice AI startups in the world, youโll love it here.
Letโs build the future together.
About The Role As a Senior Full-Stack Engineer, youโll shape the heart of Retell AIโs voice automation platform, building scalable systems and intuitive interfaces that power millions of AI-driven conversations. Youโll work across the stackโleveraging React, TypeScript, and Node.jsโto deliver fast, beautiful, and reliable solutions. Collaborating closely with the founding team, youโll bridge backend architecture (like prompt orchestration and telephony integrations) with frontend experiences (such as dashboards and analytics tools), ensuring seamless customer onboarding and impactful user experiences. This high-impact role offers rapid feedback loops, customer collaboration, and the opportunity to define a category-leading product that transforms global communication.
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Retell AI Basics: Everything You Need to Start Building Voice Agents
Join Retell AI to shape the future of voice automation, building scalable, impactful full-stack systems that redefine AI-driven communication.
Online Assessment (1.5 Hours): Coding questions on practical problem-solving (7 days to complete).
Intro Call (15-20min): Connect with our Founding Recruiter to get a deeper look at the team and the work you'd be doing.
Technical Phone Interview (45 min): Practical coding session focused on code fluency and system design (For frontend roles, we will focus on React-specific questions. For backend roles, we take a technology-agnostic approach.)
Technical Interview (45 min): A deep dive into your backend chops and how you think through systems design.
Onsite/Virtual Interviews (2โ3 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.
System Design: Architect a production-ready system.
Tools & Automation: Build automations or improve workflows in any basic environment setup like python, java, node.js, etc.