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 Block-Builder Engineer at Eureka Labs, you will take ownership of a production-grade, low-latency block-building platform and the systems around it.
You will work on the critical seal-and-submit path, block construction and bidding algorithms, parallel transaction simulation, secure builder-to-relay communication, and the off-chain logic supporting a new on-chain lending protocol and a trust-minimized TEE-based execution model.
A major part of the role is solving complex, open-ended engineering problems: improving bidding speed and efficiency, enabling capital to be safely borrowed and repaid within a single block, and creating mechanisms that prove correct system behavior without exposing competitive advantages.
Key Responsibilities
- Build and improve order-flow ingestion, bundle and transaction processing, relay submission flows, back-pressure mechanisms, and reintegration of channels into block construction.
- Develop and maintain observability tooling using Grafana, Prometheus, Loki, and SQL-based analytics, while identifying inaccurate or misleading metrics and dashboards.
- Design and execute production experiments, including A/B testing, data extraction, analysis, and clear reporting of results.
- Investigate and resolve production issues such as panics, dropped messages, latency regressions, and other reliability problems.
- Write tests and safeguards to prevent recurring failures and performance regressions.
- Contribute to optimization-driven block construction, protocol-level logic, and execution extensions such as BEX.
- Support the intrablock lending protocol by implementing both off-chain and on-chain components within the trusted-execution environment.
- Gradually expand into the exchange layer, building and maintaining high-throughput services that interact with trading systems.
Required Competence and Skills
- 2–4+ years of professional software engineering experience, including hands-on experience shipping and operating production systems.
- At least 2 years of experience working with Ethereum or other EVM-compatible blockchain protocols.
- Production experience with Rust is a strong advantage. Strong backend or systems engineering experience with Go, C++, or Java can also be considered if you are motivated and able to ramp up quickly in Rust.
- Experience working with concurrent, performance-sensitive, or real-time systems and confidence navigating a large existing codebase.
- Strong data skills, including SQL and experience using databases, logs, and production data to investigate system behavior and measure the impact of changes.
- Ability to use Python for analysis, automation, or internal tooling.
- Familiarity with monitoring and analytics tools, or a willingness to learn them, together with the ability to critically evaluate the accuracy of metrics and dashboards.
- A careful, data-driven engineering approach: validating assumptions, thoroughly testing changes, and distinguishing verified findings from hypotheses.
- Strong curiosity and ownership mindset, with an interest in understanding why production metrics change, identifying root causes, and iterating on solutions.
- Fluent English and willingness to work within Eureka Labs’ hybrid, office-first model in Poland.
Nice to Have
- Knowledge of or interest in Ethereum PBS, MEV, smart contracts, or trading systems.
- Experience with high-throughput data pipelines, time-series workloads, or large-scale analytics systems.
- Familiarity with reth, geth, or revm internals.
- Experience running production services with Kubernetes or Docker.