Ethereum block builder Eureka Labs has completed a $6.7 million seed funding round, co-led by Spark Capital and Collider Ventures. The funding was structured using SAFE and token warrant agreements and was executed in two phases: $4.7 million in April 2025 and an additional $2 million from Spark Capital in June 2025. The company's valuation remains undisclosed. Founded in December 2024, Eureka Labs ranks fourth in Ethereum block construction by volume, holding a market share of approximately 1.5%. The top three builders, Titan Builder, BuilderNet, and Quasar Builder, collectively dominate nearly 96% of the market.