Software Engineer - Backend
At a glance
Mid-level Backend Engineering role at Koah. San Francisco · full-time · $180,000–$250,000 base.
techroles summary, based on the employer's posting.
What you'll do
- Build data structures that handle several impressions per ad request while balancing publisher and advertiser interests
- Shape reusable components for trying new ad formats and recording how users engage with them
- Create a fast frequency limit system that helps prevent users from seeing too many ads
- Define structures for large volumes of exchange bidding to widen the range of available ad demand
- Refine live auction and ad selection systems to improve results for publishers, advertisers and users
What you bring
- You enjoy diagnosing slowdowns and tuning system performance
- You care about precise implementation and building abstractions other engineers can depend on
- You like testing ideas, measuring results and making systems reliable
Who this fits
This mid-level, onsite role in San Francisco suits you if you want responsibility for foundational systems. You’ll partner with product and data science to turn unclear challenges into measurable results.
From the employer
Who We Are
Koah Labs is building the ad network to power the next generation of AI-native products. Our mission is to help publishers monetize and help advertisers reach the right audience — without compromising speed, UX, or privacy.
We’re a small, tight-knit team in San Francisco with backgrounds at X, Apple, Meta and early-stage startups. We’ve raised from top investors and are growing fast with real traction on both the publisher and advertiser sides of the marketplace.
Working at Koah means joining at the ground floor: you’ll ship code that shapes the company and the ecosystem we’re building. We move quickly, operate with high trust, and care deeply about craft.
Our Stack
Infra: Terraform, AWS, LGTM (Loki, Grafana, Tempo, Mimir), Tailscale, Cloudflare
Data: PostgreSQL, ClickHouse, Redis, Kafka, Python
Core Application: Ruby on Rails, React, TypeScript
SDKs: Flutter, React Native, Android, iOS
Example projects
Build scalable data models that support multiple impressions for an ad request allowing us to align publisher and advertiser interests
Design abstractions that allow us to experiment and ship new formats that allow for a flexible way of tracking engagement events
Build a low-latency frequency capping system to improve an end user's experience and prevent ad fatigue
Create schemas to represent high-volume ad bidding with ad exchanges to increase the diversity of the ad demand on platform
Evolve our real-time auction and ad-decisioning systems to improve publisher, advertiser, and user outcomes
You might be a fit if
You like debugging and optimizing performance
You are detail oriented and like to create good abstractions that others rely on
You enjoy experimentation, measuring, and creating reliable systems
You want ownership of foundational systems
You enjoy working closely with product and data science to turn ambiguous problems into measurable outcomes
Backend Engineering work from LinkedIn, X, Reddit and Upwork, in one list.
Each morning you get everything that fits, strongest first.
Backend Engineering$180k+
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