Principal AI Platform Engineer - AdTech & Media Buying

Three Pillars Recruiting; United States; On-site; USD 180,000 - 280,000; Full time

Job summary

Three Pillars Recruiting seeks a Principal Engineer to own end-to-end areas of the product, spanning the agent harness, evaluation systems, platform integrations, and the user interface. You will work on a lean team with engineering autonomy, from idea to production, and directly with customers as media buyers use the systems you build.

You will integrate a new advertising platform, design robust APIs, and drive ownership from design through production, with strong emphasis on reliability and

Qualifications

• 5+ years backend engineering experience.
• Production Python experience or equivalent depth in another language.
• Comfort with asynchronous systems, Postgres, schema design and background jobs.
• Hands-on experience with LLM agent systems and tool calling.
• Diagnose nondeterministic systems using evaluations, replay, tracing, and telemetry.
• Frontend experience with TypeScript and React; Next.js and Tailwind helpful.

Responsibilities

• Integrate a new advertising platform.
• Own an agent-powered product surface with distinct subsystems.
• Eliminate recurring production failures using logs and traces.
• Extend the agent harness with improved tooling and review systems.

Skills

Backend engineering

Python

Async systems

Postgres

Schema design

Background jobs

Distributed systems

LLM agent systems

Tool calling

Context management

Structured outputs

TypeScript

React

Tools

Google Cloud

Vertex AI

Cloud Run

BigQuery

Pub/Sub

FastAPI

pgvector

Redis

Next.js

Tailwind

CopilotKit

AG-UI

Job description

Three Pillars Recruiting seeks a Principal Engineer to own end-to-end areas of the product, spanning the agent harness, evaluation systems, platform integrations, and the user interface. You will work on a lean team with engineering autonomy, from idea to production, and directly with customers as media buyers use the systems you build.

You will integrate a new advertising platform, design robust APIs, and drive ownership from design through production, with strong emphasis on reliability and