Senior Software Engineer, Backend

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 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 have scaled to $36M ARR with a team of 20 people, up from $5M at the start of 2025.

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 can act as frontline agents, QA analysts, and managers — continuously executing, monitoring, and improving customer interactions.

We’re growing quickly and looking for ambitious builders who want to tackle hard technical problems, move fast, and have real impact at one of the fastest-growing voice AI startups.

Let’s build the future together.

- We’re a top 50 AI app in a16z list:

- #4 on Brex's Fast-Growing Software Vendors of 2025:

- We're also one of the top ranking startups on:

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 productio...