Principal Engineer, Ads Platform

Fetch•Reston, VA

4d•Hybrid

About The Position

Fetch is building the next generation of systems that power personalized advertising experiences for millions of users, and we're looking for a Principal Backend Engineer to help define the architecture behind them. You will design, scale, and evolve the high-throughput, low-latency distributed systems that sit on the critical path of Fetch's advertising platform. These systems must make decisions and serve experiences in real time while maintaining exceptional standards for availability, correctness, efficiency, and operational resilience. At Fetch, Principal is the most senior individual-contributor engineering level, and only a small number of engineers operate here. You set technical direction the rest of engineering builds on, act as a technical peer to engineering leadership, and are the person brought in for the cross-organizational problems that have stalled major company initiatives and that no one else has solved. You own the long-term engineering strategy for the Ads platform and drive the fundamental technical shifts, major migrations, and architectural redesigns that unlock gains for the entire engineering organization. The role requires deep expertise in distributed systems and backend architecture, along with a track record of solving difficult scaling problems in production. You should be comfortable reasoning about systems operating at very high request volumes, identifying bottlenecks across the stack, and designing architectures that continue to perform as traffic, data volume, and product complexity grow. This is a hands-on, high-impact technical leadership role with influence across multiple engineering collectives. You stay in the code while operating at Principal scope, moving between architecture, implementation, debugging, strategy, and mentorship, and your work shapes how Fetch approaches distributed systems, service architecture, performance, reliability, and engineering excellence at scale. This is a full-time role that can be held from one of our US offices or remotely in the United States.

Requirements

Significant experience designing, building, and operating large-scale distributed backend systems in production, with demanding throughput, latency, availability, and reliability requirements.
Deep understanding of distributed systems: partitioning, replication, consistency models, caching, concurrency, asynchronous processing, failure modes, and coordination.
Experience diagnosing and solving performance and scaling problems across applications, databases, caches, queues, networks, and infrastructure.
Strong expertise with service-oriented or microservice architectures, APIs, event-driven systems, and high-volume data processing.
Demonstrated experience making architectural tradeoffs across relational and non-relational databases, streaming platforms, caching technologies, and other distributed storage.
Strong operational experience with production systems: observability, SLOs, incident response, capacity planning, load testing, and reliability engineering.
Track record of driving fundamental technical shifts, such as major migrations or architectural redesigns, that improved scalability, velocity, or reliability for an entire engineering organization.
Track record of solving deeply complex, cross-organizational problems that blocked major initiatives and that others had been unable to solve.
Demonstrated influence on long-term engineering strategy and architecture at the organization or company level, spanning multiple teams or organizations, including translating technical tradeoffs into business outcomes.
Experience mentoring principal and staff engineers and coaching engineering managers and technical leaders.
Ability to remain hands-on while operating at Principal scope, moving between architecture, implementation, debugging, strategy, and mentorship.
Fluency in modern backend and infrastructure ecosystems such as Kubernetes, event streaming, distributed data stores, cloud infrastructure, CI/CD, and observability tooling.

Nice To Haves

Experience building or scaling advertising, ad-serving, auction, marketplace, recommendation, or other real-time decisioning systems.
Familiarity with advertising concepts such as targeting, pacing, bidding, frequency management, attribution, incrementality, measurement, and revenue integrity.
Experience operating at very high request rates with strict tail-latency requirements, including large-scale event streaming and real-time processing.
Experience designing multi-region or globally distributed systems with high availability.
Demonstrated success materially reducing infrastructure cost while increasing throughput, reliability, or performance.
Experience building platforms that support real-time ML inference, ranking, recommendation, or personalization.
Strong judgment on where architectural complexity is justified and where a simpler system scales further and operates more reliably.
Influence beyond a single company, such as contributions to open source, standards bodies, or the broader technical community.

Responsibilities

Own the platform architecture. Define the architecture of the high-throughput, low-latency systems behind ad selection, targeting, pacing, delivery, attribution, and measurement, including the calls on partitioning, caching, consistency, concurrency, and performance as the platform scales.
Design for reliability, resilience, and operational excellence. Set how systems degrade gracefully under partial failures, traffic spikes, and downstream degradation, and establish the metrics, tracing, SLOs, and alerting that give engineering clear visibility into revenue-generating systems.
Evolve event-driven and data-intensive architectures. Guide decisions across transactional and non-transactional stores, streaming, messaging, caching, and real-time processing, balancing consistency, durability, latency, scalability, and operational complexity.
Set organization-level standards. Establish the architectural patterns and quality bar for service design, APIs, observability, reliability, testing, and operational readiness that teams across the org build on.
Drive fundamental technical shifts. Identify and lead major migrations, architectural redesigns, and platform re-foundations that unlock large scalability and productivity gains for the entire engineering organization, often through difficult incremental change.
Own long-term engineering strategy. Shape Fetch's technical direction for the Ads platform across multiple organizations, influence priorities and architecture company-wide, steer it against industry trends, and represent Fetch's technical approach in the broader engineering community.
Solve the problems no one else can. Solve deeply complex, cross-organizational problems that block major company initiatives, operating under extreme ambiguity, and lead cross-company technical alignment across Ads, Platform, Product, Data, and ML.
Multiply the org and mentor its leaders. Mentor staff and senior engineers, coach engineering managers and technical leaders on direction, and design coaching, feedback, and calibration systems that persist across teams and time.