Lead Senior Software Engineer

Penstack is hiring a Lead Senior Software Engineer on behalf of a fast-growing healthtech startup. This is a leadership engineering role, you'll design and scale the startup's core platform infrastructure while leading a geographically distributed engineering team across timezones.

You'll own the startup's data architecture, distributed systems, and real-time capabilities, working on problems that most engineers never see: syncing MongoDB to PostgreSQL at scale, orchestrating multi-tenant isolation for regulated patient data (PHI), and building real-time features across clustered Node.js processes. You'll also mentor and guide other engineers through complex architectural decisions, code reviews, and incident response.

This role requires both deep technical expertise and strong leadership presence. You'll work across timezones, make async communication a strength, and have the maturity to lead by example in a distributed team environment.

This is not a "full-stack generalist" role. You're a specialist in the hard technical problems AND a proven team leader. You understand CDC pipelines, distributed tracing, eventual consistency tradeoffs, compliance requirements, and how to ship features in a multi-tenant world where one tenant's database query can accidentally leak another tenant's PHI.

If you've built data synchronization layers, designed for compliance-driven architectures, debugged race conditions in distributed queues, AND have led engineering teams through technical challenges, this is the role for you.

Technical Leadership

• Lead engineering team architecture discussions: design systems, propose tradeoffs, and build consensus across geographic timezones. You own the long-term technical vision.

• Code review and mentorship: elevate code quality and engineer capabilities through thoughtful review, pairing sessions, and technical mentorship.

• Incident command & postmortems: lead production incident response, guide root-cause analysis, and drive process improvements across the team.

• Knowledge sharing across timezones: document architectural decisions, share async technical deep-dives, and maintain team cohesion in a distributed environment.

Data & Infrastructure Architecture

• Design and evolve the startup's Change Data Capture (CDC) pipeline: MongoDB change streams → Redis Streams → idempotent batch upserts into PostgreSQL. Optimize latency, idempotency, and failure recovery for real-time analytics.

• Lead data architecture decisions: MongoDB for transactional operations, PostgreSQL for read-heavy analytics, Redis for caching and streams. Make informed tradeoff calls on consistency models, eventual consistency windows, and per-tenant scaling.

• Build and maintain the real-time infrastructure: Socket.IO with Redis adapter across PM2 cluster mode, event fan-out, presence tracking, and distributed state consistency.

• Own multi-tenant isolation at the data layer: design schema patterns that prevent cross-tenant data leakage, write query guards, and audit access for PHI-regulated healthcare workflows (HIPAA, compliance concerns).

Team Execution

• Pair with engineers on complex technical problems: distributed systems challenges, compliance requirements, and data layer optimizations.

• Debug production incidents: trace problems across MongoDB, Postgres, Redis, job queues (BullMQ, RabbitMQ), Socket.IO. Implement observability (structured logging, distributed tracing, metrics).

• Drive testing strategy: champion unit tests, integration tests against real databases, and end-to-end tests for real-time features.

• Coordinate async communication: ensure knowledge is documented, decisions are recorded, and team stays aligned across timezones.

Core Experience

• 5–8 years shipping production full-stack systems. You've owned services from design through incident response.

• TypeScript in strict mode both backend (Node.js ES2022) and frontend (React). You know the type system deeply: generics, conditional types, discriminated unions. You catch bugs at compile time.

• Express or equivalent backend framework (Fastify, Hapi, etc.). You've built RESTful APIs, organized code into layers (controllers, services, repositories), and handled validation with schema libraries like Zod.

• React + real-time patterns (Socket.IO, WebSockets, subscriptions). You've built live dashboards, presence features, or collaborative editors. You understand how distributed processes share real-time state.

Data & Architecture (The Senior Differentiator)

• MongoDB (Mongoose) as a primary transactional store and PostgreSQL as a read/analytics store. You understand when to use each. You've optimized queries, handled indexes, and reasoned about replication.

• Change Data Capture, event streaming, or data synchronization (even if not MongoDB → Postgres specifically). You've worked with Kafka, RabbitMQ, change log tailing, or similar. You know idempotency, exactly-once semantics, and failure recovery.

• Redis caching, streams, pub/sub, or cluster mode. You've debugged memory eviction, connection pooling, and cache invalidation.

• Distributed systems concepts: eventual consistency, CAP tradeoffs, multi-leader replication, or consensus algorithms. You don't panic when a write hits one database before another.

• Multi-tenant architecture at the data layer. You've designed or audited schemas for tenant isolation, soft-deleted data, or compliance concerns. You think about query gates and accidental cross-tenant leakage.

Async, Queuing & Real-Time

• Job queues (BullMQ, RabbitMQ, Celery, etc.). You've debugged task retries, exponential backoff, dead-letter queues, and distributed locking.

• Socket.IO or similar real-time library. You understand event broadcasting, room/namespace concepts, and how to handle clusters (Redis adapter, sticky sessions, etc.).

• Scheduled jobs (node-cron, APScheduler, etc.) and the outbox pattern for reliable event publishing. You know when to use each.

Infrastructure & Integrations

• AWS (EC2, S3, or similar) or equivalent cloud providers. You've deployed, scaled, and debugged production systems.

• Process management (PM2, systemd, supervisord) and clustering. You understand forking, IPC, and shared state in multi-process environments.

• Telephony or regulated integrations a plus (Twilio, healthcare APIs, compliance frameworks). Shows you've worked in high-stakes domains.

• Webhooks, auth (JWT, OAuth), and security (bcrypt, CORS, rate limiting, 2FA). You ship secure systems by default.

Testing & Observability

• Jest or similar testing framework. You write unit and integration tests and know when to use each. You value high coverage on business-critical code.

• Structured logging, distributed tracing, or observability tooling. You ship code with hooks for debugging production issues.

• Performance profiling: You've used flamegraphs, CPU profilers, or memory analyzers. You can identify and fix N+1 queries or memory leaks.

Leadership & Distributed Team Skills (Critical for This Role)

• Proven team leadership: You've led engineering teams (even small ones) through technical challenges. You can grow talent, delegate effectively, and hold engineers accountable to high standards.

• Async communication excellence: You communicate clearly in writing. You can make technical decisions and explain them in Slack/email in a way that doesn't require immediate back-and-forth. You document decisions for future reference.

• Timezone awareness: You've worked across geographic regions. You know how to schedule synchronous time wisely, unblock teams without waiting for replies, and keep morale high in a distributed environment.

• Maturity & humility: You lead by example. You're comfortable saying "I don't know" and learning from junior engineers. You take feedback well and iterate on your leadership approach.

• Stakeholder communication: You explain technical tradeoffs to product, non-technical stakeholders, and international partners clearly and concisely.

Soft Skills & Work Style

• Communication: You express complex technical ideas clearly. You're patient and can adapt explanations to different audiences.

• Mentorship: You've leveled up engineers through code reviews, pairing sessions, design discussions, or formal mentorship. You take pride in growing talent.

• Incident response: You stay calm under pressure. You debug production fires methodically, document root causes, and lead blameless postmortems that drive real improvements.

• Ownership & accountability: You see projects through from design to launch to long-term maintenance. You own outcomes, not just tasks. You proactively raise concerns and suggest solutions.

Healthcare/Regulated Domain (Important for This Role)

• HIPAA or similar compliance awareness: You understand privacy regulations, data residency, audit trails, and consent-driven data access. You know why "this might leak PHI" is a critical blocker.

• Healthcare or regulated industry experience: You've shipped products in healthcare, fintech, or other high-compliance spaces. You know the difference between "nice-to-have" and "legally required."

• Audit & observability for compliance: You've designed systems with regulatory requirements in mind logging who accessed what data and when, supporting audit trails, handling GDPR/HIPAA deletion requests.

Nice-to-Haves (Not Required, But Valued)

• Experience with AI/ML integrations (OpenAI, embeddings, fine-tuning) for future healthtech AI features.

• Call center or contact center software (Ameyo, Zendesk, etc.) we integrate with telephony.

• Hexagonal/clean architecture patterns we use this extensively.

• Go, Rust, or systems programming experience (signals lower-level system thinking and maturity).

• Previous experience building products from early stage to scale in international/distributed startup environments.