Senior Software Engineer, Backend

Retell AI

San Francisco (CA)

On-site

USD 215,000 - 290,000

Full time

14 days+

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Benefits offered by this job

100% coverage for medical, dental, and vision insurance
$70/day DoorDash credit
$200/month wellness reimbursement
$300/month commuter reimbursement
$75/month phone bill reimbursement
$50/month internet reimbursement

Job summary

A leading Voice AI startup is seeking a Senior Software Engineer - Backend to shape the core systems for millions of AI-driven conversations. This role involves working with real-time audio and global telephony, leading complex projects, and collaborating across teams. Preferred candidates should have over two years of backend development experience, particularly in scalable systems. The compensation package ranges from $215,000 to $290,000 annually, along with various benefits including medical coverage and wellness reimbursements.

Qualifications

  • 2+ years of backend development experience.
  • Strong foundation in computer science fundamentals.
  • Experience with scalable, high-performance backend systems.

Responsibilities

  • Build foundational architecture for the platform.
  • Design scalable backend systems for performance.
  • Lead projects from architecture to production.
  • Collaborate with teams to create intuitive APIs.
  • Support onboarding and troubleshoot issues.

Skills

Backend development experience
Scalable systems design
Concurrency and distributed components
Clear communication and collaboration

Education

CS/CE/EE degree or equivalent

Job description

Join to apply for the Senior Software Engineer - Backend role at Retell AI.

This range is provided by Retell AI. Your actual pay will be based on your skills and experience — talk with your recruiter to learn more.

Base pay range

$215,000.00/yr - $290,000.00/yr

About Retell AI

Retell AI is using first principles to reimagine the call center with cutting edge voice AI. We believe voice is still the most natural way humans communicate, yet it has been trapped in outdated call centers for decades. Our mission is to bring intelligence, empathy, and speed to every phone conversation between businesses and their customers.

Since launching 18 months ago, thousands of companies now utilize Retell’s AI voice agents to handle sales, support, and logistics calls that once required large teams of human agents. Backed by Y Combinator, Altman Capital, and other leading investors, we have scaled to $30M ARR with a team of 20 people, up from $5M at the start of 2025.

Now, we’re scaling fast, and we’re 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, you’ll love it here.

Let’s build the future of voice automation together.

  • We’re a top 50 AI app in a16z list: link
  • We're also one of the top ranking startups on: link
CULTURE
  • Build the Dream Team: We hire high performers who work onsite in the San Francisco Bay Area, move fast, and collaborate deeply. Feedback is open, direct, and constant.
  • Customer obsession. We start with the customer and work backwards. Every job and task matters only if it ultimately benefits the customer.
  • Insist on the Highest Standards: We ship products you’re proud to show everyone — even if it means spending more time perfecting them.

We like to keep it real, we move fast, build fast, and change fast. That’s part of the fun for us, but we know it’s not for everyone.

About The Role

As a 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.

Key Responsibilities
  • 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.
YOU MIGHT THRIVE IF
  • Have 2+ years of backend development experience and a strong foundation in CS fundamentals (CS/CE/EE degree or equivalent).
  • Have worked on scalable, high-performance backend systems — especially anything involving concurrency, data, storage, or distributed components.
  • Take ownership like a founder and enjoy building core systems that need to be fast, reliable, and correct.
  • Thrive in fast-moving, ambiguous environments where you learn quickly and solve new technical problems.
  • Communicate clearly, collaborate well across teams, and move work forward with momentum.
  • Have startup experience or the grit to operate in a high-velocity environment — bonus points if you’ve worked on infrastructure, databases, or large-scale backend systems.
JOB DETAILS
  • Cash: 215k - 290k
  • Equity: Offer Equity
  • Location: Redwood City, CA, US
  • US Visas: Retell AI is open to sponsoring work authorization for qualified candidates, including H‑1B, TN, L‑1, E‑3, F‑1 (OPT/CPT), and O‑1 visas.
Other Benefits
  • 100% coverage for medical, dental, and vision insurance
  • $70/day DoorDash credit for unlimited breakfast, lunch, dinner, and snacks
  • $200/month wellness reimbursement (gym, fitness classes, etc.)
  • $300/month commuter reimbursement (gas, Caltrain, etc.)
  • $75/month phone bill reimbursement
  • $50/month internet reimbursement
Compensation Philosophy
  • Best Offer Upfront: Choose from three cash‑equity balance options; no negotiation needed.
  • Top 1% Talent: Above‑market pay (top 5 percentile) to attract exceptional builders.
  • High Ownership: Small teams, >$1M revenue/employee, and significant equity.
  • Performance‑Based: Offers tied to interview performance, not experience or past salaries.
INTERVIEW PROCESS
  • Online Assessment: Coding questions on practical problem‑solving (7 days to complete).
  • Intro Call (15‑20 min): Connect with our Founding Recruiter to get a deeper look at the team and the work you'd be doing.
  • Technical 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 (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.
    • 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.
Seniority level

Mid‑Senior level

Employment type

Full‑time

Job function

Engineering and Information Technology

Industries

Technology, Information and Internet

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