Senior/Staff Software Engineer

Full-time/Company: Ethena Labs

Ethena Labs is building a money-movement product on top of its stablecoin infrastructure. You’ll own payments, payouts, deposits, transfers, reconciliation, and the app-facing APIs and authentication backend that the native mobile app depends on.

Responsibilities

• Design, build, and own complex backend systems for a high-usage consumer app.
• Own the app-facing API contract: versioning, backward compatibility, client idempotency keys, consistent error model, and pagination.
• Own authentication and authorization backend, including passkey/WebAuthn relying party, session/token lifecycle, and authorization enforcement.
• Defend the auth surface with rate limiting, anomaly detection, and secure handling of PII and secrets.
• Trace and document money-paths end-to-end (API → wallet/executor/submitter/indexer → event streams → on-chain settlement) and close correctness/reliability gaps.
• Drive a test-first development approach (BDD/integration testing) and ship on a tight cadence.

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/fixing idempotency, rounding, or reconciliation bugs.
• Experience designing and owning client-facing APIs consumed by a mobile app: contracts, versioning/backward compatibility, idempotency keys, error models, pagination, and rate limiting.
• Experience building/operating authentication/authorization backends — OAuth2/OIDC, JWT session/token lifecycle, RBAC/ABAC scopes, MFA/step-up; WebAuthn/passkey experience ideal.
• Hands-on integration with financial third parties (card issuing, KYC/fiat ramp partners, payments/settlement providers), including webhooks, failure modes, and reconciliation.
• On-chain settlement literacy from the backend: nonces, gas, reorgs, RPC failures, confirmation depth — treating chain data as untrusted input.
• Strong TypeScript (or a strong path from Go/Kotlin/Rust/Java), Postgres, an event/queue system (NATS/Kafka/SQS-class), and gRPC-based service-to-service communication at production scale.
• A test-first culture: BDD/integration testing with real dependencies and fluency with agentic development workflows.

Stack

TypeScript, Postgres, NATS/Kafka/SQS-class, gRPC, WebAuthn/passkeys, OAuth2/OIDC, JWT

Skills

• TypeScript
• PostgreSQL
• NATS
• Kafka
• SQS
• gRPC
• WebAuthn
• OAuth2
• OIDC
• JWT
• REST API
• Authentication
• Authorization