Senior Infrastructure Engineer

JustAI

Agentic Marketing Platform

Senior Infrastructure Engineer

$130K - $250K•0.10% - 0.47%•San Francisco, CA, US

Job type

Full-time

Role

Engineering, Backend

Experience

6+ years

Visa

US citizen/visa only

Skills

Amazon Web Services (AWS), Google Cloud, Kubernetes, PostgreSQL, Python, TypeScript, Spark

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Neha Mittal

Founder

Neha Mittal

Founder

About the role

Infrastructure Engineer

We move terabytes of campaign and engagement data, and you''d own the foundation it all runs on.

About JustAI

We''re a YC-backed team building the AI platform that runs marketing for the world''s best companies. Marketers describe a campaign in plain language, and our platform turns it into running code that generates, tests, and executes personalized messaging across email and push at scale.

The founders

We were at X during the Elon takeover. I had to rewrite the backend infrastructure that now powers the core user and tweet services. You''ll get to work closely with us.

The role

You''ll own the foundation everything runs on: the large-scale data pipelines that feed our analytics and models, the compute and storage substrate, and the reliability, observability, and cost of the whole system. This is an early, high-ownership role. You''ll be building a lot from 01 and owning it end to end as we scale.

What you''ll do

• Own and scale our data infrastructure, including large-scale batch and streaming pipelines, warehouse design, and the storage layer behind them.
• Run and harden our compute platform: orchestration, autoscaling, resource isolation, and deployment of containerized workloads.
• Own the observability and reliability backbone (metrics, tracing, alerting, SLOs) and drive down both incidents and cost.
• Tackle the lowest-level scaling problems: data partitioning, throughput, query and scan cost, and distributed-systems failures at volume.
• Accelerate how quickly other engineers can ship code safely.

What we''re looking for

• 5+ years in infrastructure, SRE, or data platform roles, with hands-on experience building and operating large-scale systems at a low level.
• A 01 builder. You''ve stood up infrastructure from scratch and owned it as it grew, not just maintained someone else''s.
• Battle scars from lower-level, large-scale systems. You''ve run things like Kubernetes, Spark/Hadoop-class data processing, distributed storage, or high-throughput streaming in production.
• A track record of debugging hard problems at scale across failures, cost, and performance.
• Strong instincts for reliability, cost, and operability. You treat infra as a product with users.
• We care more about whether you''ve operated systems at scale than which specific tools you''ve used.
• Experience with machine learning systems a plus.

About JustAI

The future of Marketing is 1-1 hyper-personalized messaging. However, marketers spent multiple cycles setting up an "octopus" on CRM journey builders to manually write content for each persona and segment. Further, A/B testing is sequential and takes weeks to show results.

We drift away from the old school A/B testing world to dynamic testing. Companies can test 100+ messaging variants within a month, let AI optimize traffic for winning variants, and walk away with insights without operational setup overhead for every A/B test. We put companies in a state of continuous "always-on" testing.