Senior Backend Engineer, Onchain

Polymarket Polymarket · Fintech · New York, NY · Engineering

Polymarket is seeking a Senior Backend Engineer with deep blockchain knowledge to join their Onchain Execution team. This role involves building and maintaining infrastructure for their prediction market platform, focusing on systems between the product and the blockchain, such as relayers, transaction pipelines, RPC infrastructure, and settlement logic. The engineer will work on distributed systems, blockchain protocols, and high-throughput backend engineering, requiring strong fundamentals in backend development and a solid understanding of EVM networks.

What you'd actually do

  1. Build and maintain onchain execution infrastructure. Design and operate the relayer systems, transaction pipelines, and settlement logic that power Polymarket's markets end-to-end.
  2. Architect high-performance backend systems. Build reliable, scalable APIs and services that handle high transaction volumes and real-time data with low latency.
  3. Own RPC and chain connectivity. Implement and scale the endpoints and integrations that keep Polymarket reliably connected to EVM networks.
  4. Optimize performance and reliability. Push the limits of throughput and efficiency across our onchain systems, ensuring seamless operation as volume grows.
  5. Enhance security and fault tolerance. Apply best practices for secure, highly available distributed systems — especially in adversarial onchain environments.

Skills

Required

  • 5+ years of experience in backend development
  • Strong fundamentals: clean, well-tested code; solid database design (PostgreSQL or equivalent); well-structured APIs
  • Solid understanding of how EVM networks work: transaction lifecycle, gas mechanics, mempool dynamics, smart contract interactions
  • Experience with systems-level languages: Golang is strongly preferred; Rust or C++ also valued
  • Familiarity with blockchain infrastructure: RPC nodes, event indexing, relayer architectures, or similar
  • Excellent problem-solving skills and the ability to work through ambiguous, high-stakes technical challenges

Nice to have

  • Direct experience building or operating a relayer system
  • Experience with Ethereum rollup technologies (Arbitrum Nova, Optimism, etc.)
  • Experience with BFT consensus engines, libp2p, or core node software
  • Open source contributor in the blockchain ecosystem
  • Active on [ethresear.ch](http://ethresear.ch) or similar protocol research forums

What the JD emphasized

  • deep blockchain knowledge
  • EVM networks
  • relayer systems
  • RPC infrastructure
  • core blockchain node software
  • Golang is strongly preferred