Senior Backend Engineer (Web3)

We’re hiring for a fast-growing technology company building security-focused infrastructure for the next generation of digital assets and decentralised systems.The team is working on advanced cryptography, blockchain infrastructure, and future-proof tooling designed to help organisations adapt to emerging security challenges. Their products support areas such as secure wallets, identity, transaction flows, and developer tooling, with a strong focus on reliability, scalability, and user experience.This is an opportunity to join a highly technical engineering team working on complex, security-critical systems used across multiple applications and environments.The RoleWe’re looking for a Senior Backend Engineer to join the Product Engineering team. You’ll play a key role in designing, building, and maintaining backend systems, core libraries, and blockchain-related infrastructure.This is a full-time, fully remote role open to candidates based in Europe, ideally within GMT to GMT+2 time zones.Key ResponsibilitiesYou will:Own and evolve core backend libraries used across multiple products and runtimesDesign, implement, and maintain execution logic for blockchain transactions, signing flows, and protocol interactionsBuild reliable abstractions across blockchain RPCs, transaction construction, and network communicationMaintain strong security boundaries around key handling, signing, and cryptographic operationsDefine and support API stability, versioning, and backward compatibility standardsContribute to internal engineering standards, security practices, and technical documentationWork closely with product, research, and engineering teams to deliver production-ready infrastructureRequired ExperienceWe’re looking for someone with:Strong experience with Rust and TypeScript, ideally bothExperience building backend services, APIs, or libraries at production scalePractical Web3 development experience, such as Ethereum JSON-RPC, Viem, Ethers, contract ABIs, or call encoding and decodingGood knowledge of CI/CD, deployments, and containerised environmentsStrong understanding of security principles, including authentication, authorisation, signature verification, secrets management, and encryptionExperience with automated testing, including unit, integration, and end-to-end testingStrong written and spoken English communication skillsNice to HaveIt would be beneficial to have experience with:Smart wallet or account abstraction conceptsMultisig, validation flows, bundlers, or paymastersFrontend development with React or similar frameworksMobile development, including iOS or React NativeProtocol development or maintenanceDecentralised identity, encrypted messaging, or secure communicationsOpen-source contributions in Web3, cryptography, identity, or blockchain infrastructureWhy Apply?This is a chance to work on technically challenging infrastructure at the intersection of backend engineering, cryptography, and blockchain systems. You’ll be joining a remote-first team building tools designed for long-term security, scalability, and real-world adoption.k