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Ethena Labs is building a new engineering team to own Ethena Pay, a neobanking-style app built on top of stablecoin infrastructure. As a Staff/Senior Engineer, you will own the correctness and evolution of money-paths at the core of the product—payments, payouts, deposits, transfers, and reconciliation—as well as the app-facing APIs and authentication backend that the native mobile app depends on.
Your north star is ensuring money always moves correctly, exactly once, and observably; every request the Ethena Pay app makes is fast, well-versioned, and secure. This is a senior individual contributor role with real design authority over the backend. You will set the standard for how these services are built, not just execute tickets.
Key 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, consistent error models, 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 code 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 with test-first development. Deliver on a tight cadence using test-driven and behavior-driven development—you can prove the correctness of a payout path, not just its happy path.
Requirements:
- 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.
- Test-first culture matching theirs—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.
