The Tech Stack Behind a Canadian Healthcare SaaS: ChartPilot Phase 2
The Tech Stack Behind a Canadian Healthcare SaaS: ChartPilot Phase 2 We just completed Phase 2 of ChartPilot — a clinical documentation SaaS for Canadian healthcare organizations. The compliance requirements were non-trivial: PHIPA, PIPEDA, BCPIPA, and a dozen other acronyms. Here's the full stack and the decisions behind it. Data residency: All data must stay in Canada (no US hyperscaler sub-processors) Encryption at rest and in transit: AES-256, TLS 1.3 Audit logging: Every read/write must be
The Tech Stack Behind a Canadian Healthcare SaaS: ChartPilot Phase 2
We just completed Phase 2 of ChartPilot — a clinical documentation SaaS for Canadian healthcare organizations. The compliance requirements were non-trivial: PHIPA, PIPEDA, BCPIPA, and a dozen other acronyms. Here's the full stack and the decisions behind it.
The Core Requirements
- Data residency: All data must stay in Canada (no US hyperscaler sub-processors)
- Encryption at rest and in transit: AES-256, TLS 1.3
- Audit logging: Every read/write must be logged with timestamp, user, and action
- Access controls: Role-based with minimum 5 roles (admin, physician, nurse, clerk, viewer)
- Availability: 99.5% uptime SLA, self-healing infrastructure
The Stack
Backend
- Python 3.11 + FastAPI — async-first, Pydantic v2 for data validation
- PostgreSQL 16 — on a dedicated LXD container, not a managed service
- SQLAlchemy 2.0 with async driver (we can't use RDS due to data residency)
- Idempotency layer — every write gets a content hash; duplicate requests are rejected
- Outbox pattern — event-driven updates without distributed transactions
Frontend
- Next.js 14 (App Router) — SSR for initial load, then client-side navigation
- TanStack Query — server state management, background refetching
- Tailwind CSS v4 — component-based design system
- Framer Motion — clinical workflow animations
Infrastructure
- LXD containers on a dedicated host in Vancouver BC
- Cloudflare for DNS, CDN, WAF, and DDoS protection
- Cloudflare R2 for document storage (S3-compatible, no egress fees)
- Cloudflare D1 for lightweight edge metadata cache
- Self-hosted monitoring: Grafana + Prometheus + Loki
The Compliance Engineering
The hardest part was the audit log. Every API call generates a structured log entry with timestamp, user ID, action, resource ID, IP address, and content hash. These logs are append-only, replicated to a separate container, and retained for 7 years.
What We'd Do Differently
- Start with the compliance infrastructure first. We built it in Phase 2 and had to retrofit.
- Use SQLite + Litestream for the audit log specifically. Write-ahead log semantics with SQLite's simplicity would have saved us significant engineering time.
- More aggressive caching upfront. Clinical apps have high read-to-write ratios. We underestimated this at the architecture stage.
Results
- 27 automated tests passing
- 25 API endpoints documented
- 13 named staff roles supported
- 0 PHI incidents in 6 months of operation
The full architecture documentation is available on request.
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