Senior/Staff Software Engineer

Role Overview

We’re building a new engineering team at Ethena to own a money-movement product built on top of our stablecoin infrastructure. As the Staff/Senior Engineer, you own the correctness and evolution of the money-paths at the core of the product - payments, payouts, deposits, transfers, and reconciliation - and the app-facing APIs and authentication backend the native mobile app depends on.

Your north star: money always moves correctly, exactly once, and observably; and every request the app makes is fast, well-versioned, and secure. This is a senior IC role with real design authority over the backend - you set the standard for how these services are built, not just execute tickets.

Role Responsibilities

• Design, build, and own complex backend systems for a high usage consumer app.
• Own the app-facing API contract as a product: versioned, backward-compatible endpoints with client idempotency keys, a consistent error model, and clean pagination, built in partnership with the iOS team.
• Own the authentication and authorization backend, including the passkey/WebAuthn relying party, session/token lifecycle, and authorization enforcement at every API boundary.
• Defend the auth surface against abuse through rate limiting, anomaly detection, and secure handling of PII and secrets.
• Set patterns, tests, and documentation so the backend can be safely extended by any engineer, raising the correctness, testing, and security bar by example and in review.
• Trace and document money-paths end-to-end, from API through wallet/executor/submitter/indexer, event streams, and on-chain settlement, closing real correctness and reliability gaps as you go.
• Ship fast, test-first. Deliver on a tight cadence with test-driven and behaviour-driven development - you can prove the correctness of a payout path, not just its happy path.

Required Skills and Experience

• Proven experience building and operating backend systems that move real money in production - payments, exchange/settlement, lending, banking, or crypto - with a track record of preventing (or fixing) idempotency, rounding, or reconciliation bugs.
• Experience designing and owning client-facing APIs consumed by a mobile app at scale: contracts, versioning and backward compatibility, idempotency keys, error models, pagination, and rate limiting.
• Experience building or operating an authentication/authorization backend - OAuth2/OIDC, JWT session/token lifecycle, RBAC/ABAC scopes, MFA/step-up - ideally including a WebAuthn/passkey relying party.
• Hands-on integration with real financial third parties end-to-end (card issuing, KYC/fiat ramp partners, or payments/settlement providers), including their webhooks, failure modes, and reconciliation.
• On-chain settlement literacy from the backend - nonces, gas, reorgs, RPC failure, confirmation depth - treating chain data as untrusted input.
• Strong TypeScript (or a fast, credible path from Go/Kotlin/Rust/Java), with Postgres, an event/queue system (NATS/Kafka/SQS-class), and gRPC-based service-to-service communication at production scale.
• A test-first culture matching ours - BDD/integration testing with real dependencies (Testcontainers-style) - and fluency with agentic development workflows (Claude Code, MCP, skills) as a core part of how you engineer.