Staff Backend Engineer - Ads & Auctions Platform

Whatnot; Kraków; Hybrid; PLN 903,000 - 1,069,000; Full time

Benefits offered by this job

Health Insurance

Work From Home

Home office allowance

Cell phone & internet allowance

Parental leave

Wellness allowance

Childcare allowance

401k match

Dogfooding budget

Company leave policies

Job summary

Whatnot is seeking a Staff Software Engineer to join the Ads team, building the advertising marketplace at scale. You’ll lead architecture for high‑throughput, low‑latency backend systems powering auctions, bidding, pacing, ranking, and real‑time decision making.

You will mentor engineers, shape technical roadmaps, and collaborate with product and ML teams to translate marketplace problems into robust backend and algorithmic solutions. Remote/hybrid with US hubs.

Qualifications

• Bachelor’s degree in Computer Science, related field, or equivalent work experience.
• 8+ years (Staff) or 10+ years (Senior Staff) backend/distributed systems experience.
• Strong mastery of distributed systems fundamentals: consensus, partitioning, replication, coordination, sharding, state management, etc.
• Deep experience with high-throughput, low-latency services and stream processing (e.g., Kafka, Flink).
• Strong software design, algorithmic, and data-structure skills.
• Proficiency in one or more languages (e.g., Python, Go) and scripting.
• Experience with messaging, caches (e.g., Redis, RocksDB), time-series stores, and data pipelines.
• Proven track record of leading architecture and scaling core systems under high load, especially in ads, ranking, or ML serving context.
• Excellent communication skills, ability to influence cross-organizational stakeholders.
• Proven track record of delivering features end-to-end and can ship products and features lightning-fast without sacrificing quality.
• Strong ownership instincts — capable of driving projects from inception to production and beyond.
• The ability to pick up on new technologies very quickly.
• Startup experience at a high-growth company — working in fast-paced, rapidly evolving product environments with frequent experimentation (nice to have).
• Experience with ads systems (bidding, auction, attribution, measurement, etc.), infrastructure, and international commerce (nice to have).

Responsibilities

• Architect and lead high-throughput, low-latency backend systems powering ad auctions, bidding, pacing, ranking, and delivery.
• Design auction mechanisms balancing seller value, buyer experience, marketplace efficiency, and long-term ecosystem health.
• Build services for budget management, allocation, forecasting, experimentation, attribution, and measurement.
• Develop integrations between real-time auction services, ML models, data pipelines, and marketplace systems.
• Own performance, resilience, observability, and scalability of critical services.
• Define service contracts, architectural patterns, fault-isolation strategies, and capacity plans.
• Lead decisions for new auction and monetization capabilities and how experiments become durable platform infrastructure.
• Partner with product and ML teams to translate marketplace problems into backend and algorithmic solutions.
• Lead design and code reviews, mentor senior engineers, and raise the engineering bar.
• Participate in incident response, root-cause analysis, and postmortems for critical production systems.
• Develop the technical roadmap for auction infrastructure and connect investments to outcomes.

Skills

Bachelor's degree

Backend/distributed systems

Distributed systems fundamentals

High-throughput low-latency

Python

Go

Messaging systems

Redis/RocksDB

Data pipelines

Advertising systems

Ownership

Architecture leadership

Communication

Education

Bachelor's degree in Computer Science

Tools

Kafka

Flink

Redis

RocksDB

Job description

Whatnot is seeking a Staff Software Engineer to join the Ads team, building the advertising marketplace at scale. You’ll lead architecture for high‑throughput, low‑latency backend systems powering auctions, bidding, pacing, ranking, and real‑time decision making.

You will mentor engineers, shape technical roadmaps, and collaborate with product and ML teams to translate marketplace problems into robust backend and algorithmic solutions. Remote/hybrid with US hubs.