Software Engineer, AI Platform for Horizon Agents

Candidate; San Francisco (CA); On-site; USD 150,000 - 210,000; Full time

Benefits offered by this job

Flexible PTO

Medical, dental, vision

Life insurance & disability

Retirement plan

Parental leave

Equity plans

Snacks & coffee

Job summary

Sierra is the leading platform for customer-facing AI agents, based in San Francisco with offices across North America, Europe, and Asia. We are seeking engineers to build scalable, end-to-end production systems and reusable infrastructure for Horizon agents.

Join a team that blends customer problem solving with platform development, delivering multi-channel solutions and durable product capabilities. Expect direct customer interaction and a fast-paced, collaborative environment.

Qualifications

• Production systems experience at scale.
• Strong platform and systems engineering fundamentals.
• Ability to move between customer problems, design and implementation.
• Strong technical judgment in fast-changing environments.
• Builder’s mindset to take products from zero to one.
• Experience working directly with customers and understanding complex business processes.
• High agency, adaptability, and clear communication.
• At least two years of professional software engineering experience.
• Experience with Python, TypeScript, or Go and React.

Responsibilities

• Build primitives for self-improvement: feedback loops, evaluation systems, memory, signals, and decisioning infrastructure that help long-running agents learn from outcomes and improve over time.
• Build the future of long-horizon agents: design and ship agents that pursue complex business outcomes over days, weeks, or months across voice, SMS, email, and other channels.
• Turn 0-to-1 work into a platform: identify patterns and build reusable systems, abstractions, and tools that make future Horizon agents faster and easier to launch.
• Solve technically complex problems: build across orchestration, integrations, data, memory, signals, decisioning, observability, and multi-channel engagement.
• Shape the Horizon product: surface platform gaps through hands-on implementation and work with product and engineering to define Horizon’s architecture and roadmap.
• Create a clean path beyond the POC: once a solution is validated, translate what you built into durable product capabilities and enable a successful handoff for continued deployment.

Skills

Systems engineering

Platform fundamentals

Software engineering

Customer empathy

Technical judgment

Python

TypeScript

Go

React

2+ years exp

Job description

Sierra is the leading platform for customer-facing AI agents, based in San Francisco with offices across North America, Europe, and Asia. We are seeking engineers to build scalable, end-to-end production systems and reusable infrastructure for Horizon agents.

Join a team that blends customer problem solving with platform development, delivering multi-channel solutions and durable product capabilities. Expect direct customer interaction and a fast-paced, collaborative environment.