Senior Backend Engineer

**The Opportunity**:
A growth-stage B2B / Saas / Data Platform client of ours processes ~10 k req/s and ~3 TB of relational data today; customer onboarding this quarter will push volumes **5-100×**. Hotspots already appear in Sequelize‑generated queries, throttling Aurora PostgreSQL and driving up AWS spend.
**Why Is this role open?**:
Our client needs a senior engineer who lives and breathes **SQL performance** to get them ahead of that curve (I.e. prep & plan to scale up data volumes immensely!).
**Current Stack**:
- ** Node.js (v16+) / TypeScript** - Express.js - Sequelize ORM
- ** Aurora PostgreSQL 15** primary, **Redis/ElastiCache** for low‑latency cache
- AWS ECS Fargate - Docker - GitHub Actions CI/CD
- Observability: New Relic, pg_stat_statements, auto_explain
- Auth: JWT today, migration to Stytch planned Q4
- Tests: Jest (unit, integration with Testcontainers‑Postgres)
**What You’ll Do (Key Outcomes)**:
- ** Profile & eliminate** the top 10...