Senior Backend Engineer

The Platform team is the engine room of Antithesis - we own the infrastructure, services, and tools that are at the core of the product. As a Senior Backend Engineer here, you won't be maintaining someone else's abstractions. You'll be designing them from scratch, owning them end-to-end, across the full stack: from raw binary formats and block compaction all the way up to the external APIs our customers depend on.

Correctness and performance aren't nice-to-haves here - they're the job.

If you get unreasonably excited about systems design, performance, storage efficiency, clean API contracts, and finding the bottleneck nobody else noticed, we'd love to talk.

- Design, build, and operate core platform systems - including backend infrastructure, data processing pipelines, storage layers, and the scalable APIs, integrations, and interfaces that power internal and external consumers.

- Contribute to Pangolin, our purpose-built database designed from the ground up to meet the unique demands of our platform.

- Build and evolve foundational platform primitives such as data access layers, authorization frameworks, and service orchestration.

- Own reliability end-to-end - from system design and capacity planning to incident response, with a sustainable on-call rotation shared across the team.

- Identify and resolve performance bottlenecks across the stack; mentor engineers; contribute to long-term technical strategy.

- 5+ years of software engineering experience. Rust is a strong preference, but exceptional systems engineers from other backgrounds are welcome.

- Experience building APIs, services, storage engines, query engines, or data-intensive backend systems.

- Deep understanding of distributed systems: consistency, fault tolerance, replication, observability.

- Hands-on experience designing and shipping APIs with attention to correctness and contract stability.

- Strong fundamentals - you care about correctness, test coverage, and well-designed abstractions.

- Bonus: query planning/optimization experience, multi-tenant platform or authz background, C/C++ familiarity, or open-source contributions.

Our team has backgrounds spanning CS degrees, philosophy, mathematics, and everything in between - or nothing formal at all. What everyone shares is a high bar for engineering quality, regardless of title. We work in-person because it's how we build trust and tackle hard problems together.

Location: This position is in office in Vienna, VA.