Senior Backend Engineer, Developer Platform

Job description

At Offchain, we aren’t just building products: we’re leading a movement. As pioneers in blockchain scalability and security, we're at the forefront of transforming how the world interacts with decentralized applications. We're laying the foundation that will define the next generation of digital commerce, governance, and human interaction. This involves tackling real-world challenges that come with scaling blockchain technology, without compromising on its core principles: decentralization, security and transparency. At the center of this vision is our people. Our team is made up of thinkers and doers that embrace new challenges and seek solutions that push existing boundaries. If you’re energized by solving unprecedented problems, and believe in the role that decentralized systems will play in creating a more equitable digital future, then we want to hear from you. **Why Offchain?** Offchain is setting the pace for the entire Ethereum ecosystem. We built the Arbitrum stack that powers Arbitrum One, the most widely adopted Ethereum scaling solution that exists today. Arbitrum’s ecosystem is undergoing tremendous growth with hundreds of projects and dApps on Arbitrum One today. Over 100 different teams have used Offchain technology to build their own Arbitrum chains. Major players in the space, Robinhood, BlackRock, Ethena Labs, Securitize, Aave, and Apechain are all using the Arbitrum stack. Arbitrum’s thriving ecosystem wouldn’t exist without our advanced technology stack. Arbitrum, Prysm, ZeroDev. These aren’t just product names. These are tools that are actively reshaping what's possible on Ethereum and advancing its core infrastructure. To top it all off? We’re backed by $124 million in funding. We’ve demonstrated consistent execution with billions in secured value, thousands of supported projects, and infrastructure processing millions of transactions seamlessly. ### The Role: The Developer Platform team builds KMS, the key-management and signing service behind ZeroDev's embedded wallets (smart-account / account-abstraction wallets that app developers drop into their products). It is non-custodial: end users control their keys, and the service orchestrates secure creation, authentication, and signing on top of a third-party signing provider. This is security-critical infrastructure, externally audited, with a high review bar. You will own backend services and the cryptographic recovery and trust-model machinery around them on a small, high-ownership team, and help grow the platform from interactive consumer wallets toward programmatic and automated signing and programmable transaction policy. ### What you'll work on: - Go backend services that broker wallet creation, authentication, and signing at scale. - Key recovery and the committee trust model: distributed key generation and secret sharing that keep the service non-custodial, with recovery authority split across independent committees so no single party ever holds a user's key - Trusted Execution Environments: reconstructing and operating on key material under hardware isolation and remote attestation - Authentication and signing-provider integration: the user-facing auth methods that gate signing (passkeys / WebAuthn, OAuth, OTP, sessions, 2FA), and integrating with a third-party signing provider (authorization and policy flows, scoped credentials, quorum / consensus approvals) - Security review and hardening: writing design docs and decision records, working directly with external security auditors, and turning a high review bar into shipped code - Production operations on Kubernetes: observability and alerting, secrets and certificate management, on-call, and the compliance controls the domain requires (sanctions screening, PII-safe handling) ### Who you are: - A strong backend engineer who has shipped and operated production services in Go (or an adjacent systems language and is eager to go deep in Go) - Security-first by default: you reason about threat models, blast radius, and key custody as a habit, and you write code that holds up to security-critical review - Comfortable with applied-cryptography fundamentals (public-key crypto, signatures, key management). You do not need to be a cryptographer, but you can reason about it and learn fast - Solid on distributed systems and API design: idempotency, failure modes, and clean service boundaries - Operationally mature: Kubernetes, observability, and incident response are not foreign to you - Clear written communicator (design docs, decision records) who thrives in a collaborative, review-heavy culture Nice-to-have - TEE experience (AWS Nitro Enclaves, Intel SGX / TDX, or similar): attestation, enclave key handling, reproducible enclave builds - Threshold cryptography / MPC in practice: DKG, FROST or other threshold signatures, verifiable secret sharing, resharing - Account abstraction: ERC-4337, EIP-7702, smart-account or embedded / non-custodial wallet experience - Built on or integrated a custody / signing provider (Turnkey, Fireblocks, or similar), or built one - HSM / YubiKey / PIV / secure-element integration - Been on the receiving end of a third-party security audit and driven the remediation - WebAuthn / passkeys, OAuth / OIDC, and the Go crypto ecosystem ### Perks: - Remote-first global workforce + NY office - Professional reimbursement program (facilitates industry conference attendance, certifications, and more) - Medical, dental & vision coverage (US + some other countries) - 401k retirement plan + company match (US only) - Wellness stipend - Home office set up / ergonomic equipment program