Senior Software Engineer - Infrastructure

AfterQuery; San Francisco (CA); On-site; USD 180,000 - 240,000; Full time

Job summary

AfterQuery is seeking a Senior Software Engineer - Infrastructure in San Francisco to design and build core infrastructure for data generation, evaluation, and AI workflows. You will own systems powering large-scale experiments and ensure they are scalable and reliable.

You will collaborate with the founding team to set architecture, establish engineering standards, and develop platforms that support high-throughput workloads, observability, and robust data pipelines for frontier AI models.

Qualifications

• Extensive experience building production distributed systems.
• Strong Python and/or JavaScript (Node.js/Next.js) skills.
• Experience designing/operating systems in cloud environments (GCP/AWS).
• Familiar with messaging systems (Kafka, RabbitMQ, Pub/Sub).
• Experience with high-throughput data pipelines and asynchronous processing.
• Proven ownership of production systems.

Responsibilities

• Architect and develop shared infrastructure powering data generation platforms.
• Build scalable systems with high-throughput workloads and reliability.
• Create reusable APIs for product engineers and researchers.
• Design observability, monitoring, and fault tolerance for production.
• Define long-term data pipelines, compute, orchestration, and storage.
• Collaborate with researchers to enable AI experimentation workflows.
• Set standards for system design, deployment, and operations.

Skills

Distributed systems

Python

JavaScript (Node.js/Next.js)

Cloud platforms (GCP/AWS)

Data pipelines

Observability & monitoring

Production ownership

Tools

Kafka

RabbitMQ

Pub/Sub

Job description

Senior Software Engineer - Infrastructure

Role Overview

As a Senior Software Engineer - Infrastructure at AfterQuery, you will design and build the core infrastructure that powers our data generation, evaluation, and agentic systems.

You will be responsible for the shared platforms that enable our engineers and research teams to run large‑scale human‑in‑the‑loop workflows, evaluation harnesses, and automated data pipelines used to train frontier AI models.

This is a highly technical role with broad ownership. You will architect and build foundational infrastructure that many other engineers depend on, ensuring systems are scalable, reliable, and capable of supporting extremely high‑throughput workloads.

You will work directly with the founding team to define system architecture, establish engineering best practices, and build the infrastructure that supports the next generation of AI development.

Why Apply

Massive Opportunity: We were one of the fastest‑growing YC companies in our batch, and we believe we can become one of the fastest‑growing YC companies of all time.

Founding Impact: You will own and architect core infrastructure systems that power our platform from the ground up.

Equity & Growth: Competitive salary and meaningful equity. As we scale, you’ll have the opportunity to shape the engineering organization and lead major technical initiatives.

Strong Team: Our founding team has experience from Citadel Securities, Meta, Google, Silver Lake, and Morgan Stanley — work alongside world‑class engineers and researchers.

Responsibilities

• Architect and develop the shared infrastructure powering our data generation platforms, human‑in‑the‑loop systems, and evaluation pipelines.
• Build systems capable of processing large‑scale datasets and high‑throughput workloads with strong reliability guarantees.
• Create reusable infrastructure and APIs that enable product engineers and researchers to build quickly and reliably on top of core systems.
• Design systems with strong observability, monitoring, and fault tolerance to support production workloads at scale.
• Help define long‑term system architecture across data pipelines, compute infrastructure, task orchestration, and storage systems.
• Work closely with engineers and researchers to support new AI experimentation workflows and platform capabilities.
• Define standards for system design, deployment, reliability, and infrastructure operations.

Required Qualifications

• Strong experience building production distributed systems or platform infrastructure.
• Proficiency in Python and/or JavaScript (Node.js / Next.js) or similar backend technologies.
• Experience designing and operating systems in cloud environments (GCP or AWS).
• Experience with message queues and event‑driven systems (Kafka, RabbitMQ, Pub/Sub, etc.).
• Experience working with high‑throughput data pipelines and asynchronous processing systems.
• Strong understanding of system scalability, performance, and reliability.
• Experience owning systems running in production environments.

Preferred Qualifications

• Experience building internal developer platforms or shared infrastructure.
• Experience supporting large‑scale data processing pipelines.
• Experience with AI infrastructure, LLM evaluation systems, or ML pipelines.
• Experience working at high‑growth startups or scaling early infrastructure.
• Experience designing human‑in‑the‑loop or workflow orchestration systems.