Senior Backend Engineer — Broker API Integration (TypeScript / Node)

Senior Backend Engineer — Trading Platform API Integration Context We need a senior TypeScript backend engineer to wire up the missing pieces, mainly a third-party broker integration. Full details under NDA on the first call. Already in production Dashboard: Next.js 16, React 19, Tailwind v4 — 8 refactored pages Auth & payments: Supabase Auth, Stripe, Sumsub KYC Risk engine: Rust, running in production Infra: Docker Compose on a dedicated server, Traefik SSL, Postgres + TimescaleDB, Redis, Centrifugo (WebSocket), Sentry CI/CD: GitHub Actions, staging + prod (currently degraded) Legal, branding, domain, transactional emails: done Scope 1. Broker API integration (~60%) We have REST + WebSocket access to a major broker. You'll: Build OAuth flow + encrypted token storage with refresh logic in Postgres Implement master-level account provisioning via REST Wire WebSocket sync: push account state events (riskStatus, cashBalance, positions, fills) to the equity_history table Build reconnection logic (exponential backoff, idempotent) Handle rate limits (429 + penalty ticket mechanism) 2. Risk rule wiring (~20%) Detect breach events (daily loss, max drawdown, profit target) Trigger force-liquidation via REST on breach Update DB state for the UI Account reset endpoint 3. CI/CD fix (~10%) deploy.yml is failing on git fetch from the prod server (expired auth token). Renew via SSH deploy key (preferred) or PAT rotation. Restore staging + prod paths. 4. Observability (~10%) Structured logging for the integration layer Sentry alerting on breach events Health endpoint + basic metrics Document the data contract with the Rust engine Stack TypeScript strict · Next.js 16 API routes (App Router) · Supabase (Postgres) · SWR · Docker Compose · GitHub Actions · Sentry · Centrifugo · read-only exposure to a Rust engine Requirements 5+ years backend / full-stack TypeScript WebSocket + REST integration at scale (1000+ concurrent connections in production) Postgres: schema design, transactions, query optimization Strong async patterns, retry logic, idempotency Prior work handling money (broker APIs, payment processors, exchanges, custodial APIs) Docker + GitHub Actions TypeScript strict — no any Bonus (higher rate) Trading platforms, brokerage tech, prop firms, or market data infrastructure Order types, P&L, margin math, drawdown logic TimescaleDB / time-series Postgres Rust read-fluency (parse, not write) Not in scope Frontend, mobile, marketing site, customer support. Engagement 3-month contract, $60-90/hr USD (DOE), 30-40h/week 100% remote, CET ± 4h overlap required Possible conversion to full-time + equity after 3 months Async-friendly: weekly 30-min sync, no daily standups Start within 2 weeks Process 20-min screen call (NDA first) 45-min technical deep-dive 60-min pair-programming on our codebase References Two weeks max from first call to offer. To apply One paragraph on a real-time or money-handling API integration you shipped (tech, what broke, how you fixed it) Link to TypeScript code (repo, PR, or gist) Confirm timezone (CET ± 4h) Hourly rate I read every proposal. Skip generic templates. — Jules