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.

About Retell

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 to $7M ARR in 12 months.

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

Video Walk Through About The Product:

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

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

Vision

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

Join us—because the future of AI voice agents is coming anyway, so why not be the one who defines it?

Role Overview

The Founding Senior Software Engineer at Retell is at the core of the AI voice agent revolution. You’ll work across the entire tech stack—shipping critical features, creating delightful developer experiences, and scaling infrastructure that powers millions of phone calls. From robust backend APIs to intuitive UIs and global telephony systems, you'll help build the foundation businesses use to automate conversations at scale.

This role is perfect for ambitious engineers who move fast, take full ownership, and want to make a real impact. You’ll collaborate closely with founders, designers, and customers to bring powerful features to life. Whether it’s enabling international call deployments, building fast prompt iteration tooling, or debugging critical production issues—you’ll do whatever it takes to help customers succeed and Retell grow.

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.

Job Description

Roles and responsibilities

• Design and ship core product features that power a production-grade AI voice platform—ranging from prompt management and testing workflows to real-time monitoring, analytics, and global telephony infrastructure.
• Build scalable, reliable systems across the stack—including backend services, intuitive frontends, and DevOps workflows—that support millions of calls and scale as our customer base grows rapidly.
• Lead engineering initiatives end-to-end, from initial technical design and architecture to implementation and deployment. You'll own ambiguous problem spaces and make high-leverage technical decisions that define our platform's foundation.
• Collaborate cross-functionally with designers, product managers, and fellow engineers to craft a user experience that’s simple, powerful, and enables customers to self-serve—getting to production in hours, not weeks.
• Work directly with customers to support onboarding, debug complex issues, and incorporate feedback into product improvements. You’ll play a key role in delivering not just a product, but a reliable, high-trust experience.
• Continuously improve engineering velocity by refining internal tooling, test frameworks, and observability—ensuring the team can move fast without compromising quality or stability.

Qualifications

• 1+ years React experience
• 1+ years Typescript experience
• Strong HTML, CSS and JavaScript experience
• Bachelor's degree or equivalent practical experience.
• A founder-like mindset with a passion for taking responsibility and making a significant impact.
• Ability to thrive in a fast-paced environment, quickly learning and adapting to new challenges.
• Excellent communication and collaboration skills, with the ability to commit to decisions even when there are disagreements.
• Previous startup experience is a plus.
• Previous cloud tech stack management experience is a plus.

Benefits

• Competitive salary with an equity package and year-end bonus
• Best health, dental, and vision insurance available, 100% covered by Retell for you
• Catered breakfast, lunch, and dinner every day
• Monthly commute expenses fully covered
• Unlimited snacks and drinks
• Monthly wellness reimbursement that you can spend on anything health-related
• H1B and Green Card sponsorship available
• The chance to innovate and push the boundaries of voice AI in a dynamic, venture-backed startup

Interview Process

Online Assessment:

The online assessment will be sent via HackerRank. It consists of two coding questions and takes approximately 25–30 minutes to complete. Candidates have 7 days to submit their responses.

Phone Interview 1:

A 30-minute interview focused on data structures and algorithms.

We will share a pair programming IDE link (CoderPad), and you may use your preferred programming language.

Phone Interview 2:

A second 30–45 minute interview focused on data structures and algorithms.

We will again share a pair programming IDE link (CoderPad), and you may use your preferred programming language.

Onsite:

This step involves 1–4 hours of interviews, conducted onsite in the San Francisco Bay Area. If the candidate lives outside of the Bay Area, the interviews may be conducted virtually.

Please bring a computer for writing code during the interviews.

There are up to four interview rounds:

• A practical coding session involving day-to-day coding tasks, documentation lookups, and debugging.
• A system design interview covering a high-level overview of the production system components. This provides candidates with a comprehensive view of our technical requirements and work environment.
• A practical tools session focused on building automations or using tools commonly used by software engineers.
• A behavioral interview covering past work experience and work style.