Block-Builder Engineer

Adaptiq, on behalf of Eureka Labs, is looking for a Block-Builder Engineer

About the Eureka Labs:

Eureka Labs runs a next-generation Ethereum block builder that operates live on mainnet across multiple regions, processing high volumes of DeFi transactions and competing in sub-millisecond latency auctions. It augments Ethereum’s capabilities, unlocks new DeFi primitives like intrablock lending, and enforces neutral, verifiable block construction via trusted execution. 

About the Role:

As a Senior Block-Builder Engineer at Eureka, you will own a production-grade, low-latency block-building platform and the systems that extend it: the seal-and-submit critical path, block-construction and bidding algorithms, parallel simulation, secure builder↔relay communication, and the off-chain logic that connects to a new on-chain lending protocol and a trust-minimized (TEE-based) execution model. You'll turn open-ended problems - "how do we decide and bid faster than the competition," "how do we let capital be borrowed and repaid safely inside one block," "how do we prove we behaved honestly without exposing our edge" - into shipped, measurable systems.

Key Responsibilities:

• Integrate and process sources: implement order-flow ingestion, bundle and transaction handling, relay submission paths, back-pressure controls, and channel reintegration into each block.
• Develop observability as a product: build and improve Grafana, Prometheus, Loki telemetry, and SQL analytics; identify and fix misleading counters and dashboards.
• Design and run production experiments: configure A/B tests, extract data, analyze results, and report clear conclusions.
• Ensure system reliability: diagnose and fix panics, dropped messages, and latency regressions; author tests to prevent regressions.
• Collaborate on optimization-driven block construction, contributing to protocol-level logic and execution extension (BEX).
• Support the on-chain intrablock lending protocol: implement off-chain and on-chain components within the trusted-execution layer.
• Ramp into the exchange layer: design and maintain high-throughput services that interface with trading systems.

Required Competence and Skills:

• At least 2-4 years of professional software engineering experience, with hands-on experience shipping and operating software in production.
• At least 2 years of experience with Ethereum or EVM-compatible blockchain protocols.
• Production Rust experience is a strong plus. Solid backend or systems engineering experience in Go, C++, or Java, combined with a strong motivation and ability to become productive in Rust, will also be considered.
• Comfort working with concurrent and real-time systems and navigating a large existing codebase.
• Strong data fluency, including SQL and experience working with databases or logs to investigate system behavior and validate whether changes actually improved performance. Comfortable using Python for analysis or tooling.
• Familiarity with or willingness to learn monitoring and analytics tooling, with the ability to identify when metrics, counters, or dashboards may be misleading.
• Careful and data-driven engineering habits: you test your work thoroughly, validate assumptions against production data, and clearly distinguish between what is verified and what is assumed.
• Curiosity and self-direction: you are motivated to investigate why production metrics change, identify root causes, and iterate on solutions rather than simply closing assigned tasks.
• Fluent English communication skills and willingness to work within Eureka Labs’ hybrid office-first model in Poland.

Nice to Have:

• Interest in or exposure to Ethereum/PBS/MEV, smart contracts, or trading systems.
• Experience with high-throughput data pipelines, time-series processing, or large-scale analytics.
• Exposure to reth/geth/revm internals or running services on Kubernetes/Docker.