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 $7M ARR in 12 months.

Check us out on the Top Lean AI Native Companies Leaderboard at leanaileaderboard.com.

Retell AI - API That Turns Your LLM Into A Human-Like Voice Agent

Retell AI Basics: Everything You Need to Start Building Voice Agents

Why This Company

Twenty years ago, every business found itself needing a website, the new gateway to the world. Platforms like WordPress and Squarespace rose to become the standard for getting businesses online.

Today, we’re at the start of a new shift. Every business that relies on phone interactions can now have an AI voice agent of their dreams. A tireless and empathetic receptionist, salesperson, debt collector, or appointment reminder that works 24/7. Operational bottlenecks vanish overnight. Doubling your business no longer means doubling your team. Customer experience no longer suffers. (Ever tried calling an East Coast bank after 3 p.m. PT?) But companies aren't ready. Platforms don't exist.

At Retell, we're building the new standard for building AI voice agents. A seamless UI, a comprehensive toolkit, effortless integrations, and a thriving builder community, we're creating everything businesses need to deliver exceptional phone interactions on every single call.

This shift is happening, so why not be part of the team that defines it?

Why This Role

This is a high-impact role for engineers who want to move fast, take ownership, and help build a category-defining product from the earliest days. As a Founding Senior Software Engineer, you won’t just be shipping features—you’ll shape the core systems and experiences that power millions of automated conversations.

You’ll work across the stack, solving tough technical challenges in real-time audio, global telephony, and developer tooling. You’ll collaborate closely with the founding team, talk to customers, and ship improvements weekly—sometimes daily.

If you’re excited by big problems, fast feedback loops, and the opportunity to help define how businesses use voice AI at scale—this is the role for you.

Position: Founding Senior Software Engineer

Job type: Full-time 70hr/week (50 hr/week onsite with flexible hours + 20 hr/week work from home)

Salary: $200K - $310K

Equity: 0.50% - 1.0%

Bonus: $20k - $100K

Location: San Carlos, CA, US

US visas: Sponsors Visa & Greencard

Benefits: 100% medical, dental, vision insurance covereage. Unlimited breakfast, lunch, dinner, and snacks. Gym, daily communte fee reimbursed. Internet, phone bill covered.

Who You Are

• Frontend Pro, React-Lover – You’ve got 1+ years of experience building production-grade apps with React and TypeScript. You’re fluent in HTML, CSS, and JavaScript, and bring clean design thinking to every line of code.
• Technically Grounded – You hold a degree in Computer Science, Computer Engineering, or equivalent practical experience—and you’ve used it to build real things that people use.
• Ownership-Driven – You think like a founder, take initiative, and chase impact. You don’t wait to be told what to do—you identify problems and solve them.
• Quick, Curious, & Collaborative – You thrive in fast-moving environments, learn new tools and frameworks quickly, and enjoy working across teams to get things done.
• Startup-Ready – You’re familiar with cloud stacks and love the chaos (and clarity) of small teams. Startup experience is a plus, but a scrappy, adaptable mindset is essential.

What You’ll Do

• Build the Core Experience – Design and build mission-critical features of our AI voice platform—prompt management, test tooling, dashboards, analytics, and more. You’ll bring UI to life and own the user journey.
• Work Across the Stack – From backend APIs to polished UIs to DevOps workflows—you’ll build systems that power millions of calls and scale with our growing customer base.
• Own Big Projects – Take engineering projects from concept to launch—leading technical architecture, coding, deployment, and iteration.
• Craft Great UX – Collaborate with designers, PMs, and other engineers to create fast, intuitive, and beautiful experiences that get users activated in hours, not weeks.
• Partner With Customers – Work directly with users to support onboarding, debug tough issues, and turn feedback into features that drive trust and long-term success.

Our Compensation Philosophy

• Our Strongest Offer, Upfront
  We give you our best offer from the start. No need to negotiate or match other companies offer — instead, we offer three clear compensation options, each with a different balance of cash and equity. You pick what fits you best.
• Designed for Talent Density
  We’re building with the top 1%, not the average. That’s why our compensation is set far above market — to attract people who raise the bar for everyone around them.
• Scale Through Code, Not Headcount
  We aim for >$1M in revenue per employee. That means smaller teams, fewer layers, and higher ownership per person — both in terms of scope and equity.
• Performance > Background
  We don’t anchor to other companies, past salaries, or industry ranges. Your offer is based entirely on your performance in our interview process. That’s it.
• Experience Doesn’t Dictate Pay
  Your offer is based solely on how well you perform in the interview process. We don’t factor in past salaries, titles, or number of years worked. You can earn our highest tier with zero years of experience — if you prove you’re ready for it.

Interview Process

• Online Assessment – We’ll kick things off with a short HackerRank assessment—two coding questions, 25–30 minutes total. You’ll have 7 days to complete and submit it.
• Phone Interview 1 – A 30-minute live coding session focused on data structures and algorithms. We'll share a CoderPad link, and you’re free to use your preferred language.
• Phone Interview 2 – A 30–45 minute technical interview with a focus in full-stack development using javascript, typescript, react and node JS.
• Onsite Interviews – These take 1–4 hours and are conducted in person in the San Francisco Bay Area. Please bring a computer for any hands-on portions. For remote candidates, we’re happy to arrange virtual sessions. There are up to four rounds:
  • Practical Coding Session – Tackle real-world coding tasks, referencing documentation and debugging along the way.
  • System Design Interview – Walk through the architecture of a production-ready system and share your high-level thinking.
  • Tools & Automation Session – Build automations or use common developer tools to improve workflows.
  • Behavioral Interview – A conversation about your past experience, decision-making, and work style.