A proven enterprise blueprint for building scalable, reliable, performative, and cost-efficient SaaS platforms.
Open-source · vendor-neutral · production-validated.
EPAS is a comprehensive architecture specification for enterprise SaaS platforms. It codifies the patterns, controls, and decisions required to ship a multi-tenant, multi-region, AI-capable platform that enterprises will buy and auditors will accept.
The specification is vendor-neutral in spec text — no cloud, language, or model is privileged — and production-validated against real enterprise workloads. 18 sections, 7 appendices, ~250 technologies cataloged.
Cloud Well-Architected frameworks were written for stateless web services. AI governance documents were written by lawyers. The result in most organizations is a stitched-together stack of cloud pillars, vendor patterns, and bolt-on compliance — coherent in slides, brittle in production, expensive in audit.
EPAS closes the gap with one integrated specification covering tenancy, identity, APIs, events, observability, FinOps, AI governance, security, compliance, DR/BC, ITIL operations, and developer experience.
- Environment-first hierarchy:
environment → org → BU → team → project → resource - Multi-tenant by design; logical or physical isolation per tenant tier
- MCP-first extensibility and Agent-to-Agent (A2A) architecture
- Event-driven core with full decision matrix across Kafka, NATS, EventBridge, RabbitMQ, and Pulsar
- Field-validated SLAs: p95 1000–2000ms by tier, 99.95–99.995% uptime
- Disaster recovery: RPO 15-minute, RTO 4-hour, multi-region replication, quarterly drills
- ITIL v4 alignment across Incident (P0–P4), Change (CAB / ECAB), and Service Management
- Change management governance for standard, normal, and emergency release tracks
- OpenTelemetry + LGTM observability with per-entity latency budgets
- Event substrate selection criteria documented and matrixed — not opinion
- Capacity planning and scaling triggers specified per workload class
- Developer experience targets measured: <60 min time-to-first-commit, <4 hr time-to-productive
- A2A cost attribution with per-agent token tracking and BU chargeback
- Real-time budget alerts at 75% warning / 95% critical thresholds
- Multi-model AI strategy: 8 providers with cost-based routing and declared fallback
- Reference workload achieves 24.5% optimization through caching + routing — full cost model published
- Security: TLS 1.3, AES-256, mTLS, zero-trust internal calls, SPIRE / SPIFFE workload identity, SBOM and supply-chain provenance
- Compliance: HIPAA, GDPR, EU AI Act, BIPA, ISO/IEC 42001, NIST AI RMF; vendor management aligned to GDPR Article 28 / SOC 2 / ISO 27001
- AI Governance: model approval workflow with explicit RACI (CAIO accountable; CISO, CIO consulted), evidence matrices mapping regulation to capability to artifact, audit trail requirements specified
- Developer Experience: one-command setup, LocalStack, mkcert, hot-reload, environment parity
The full specification lives in Enterprise_MultiPlatform_Architecture_Scaffold.md. Where to begin depends on your role:
| Role | Recommended Sections | Appendices |
|---|---|---|
| CFO / COO | §9 A2A Cost Tracking & FinOps | Appendix A — Cost Model |
| CTO / CIO | §11 Event-Driven Architecture · §21 Developer Experience | Appendix C — Event Bus Matrix |
| CISO | §15 Security Architecture & Hardening | Appendix D — Security Checklist |
| CAIO | §10 Multi-Model AI Strategy · §14 Regulatory Compliance & AI Governance | Appendix E — Decisions Log |
| CRO / CLO | §14 Regulatory Compliance | Appendix B — Regulatory Checklist |
| Operations | §16 Incident Response · §17 DR/BC · §20 Change Management | — |
| Architects | §2–6 Core Architecture, Identity, Tenancy, APIs, MCP/A2A | — |
The Technology Index catalogs ~250 technologies, frameworks, tools, and standards referenced across the spec.
The specification is vendor-neutral, but illustrative reference choices are documented:
- Event Bus: Kafka / Redpanda (Phase 1), NATS / JetStream (Phase 2, latency optimization)
- LLM Primary / Fallback: Claude Sonnet · OpenAI GPT-4o
- Voice: Deepgram Nova-2 (STT), ElevenLabs Turbo v2.5 (TTS)
- Identity: Zitadel + OpenFGA + SPIRE
- Observability: OpenTelemetry + Grafana LGTM stack
Not a certification. Not legal advice. Not a vendor pitch deck. Reference implementations exist but are explicitly out of scope for the normative document.
Apache 2.0 — see LICENSE.
Nate Walker — Founder, Ravenhelm. ~20 years in enterprise AI presales, solution architecture, and platform strategy at IPsoft, Amelia, SoundHound, and Quant.ai. Speaker: Gartner, Forrester, NVIDIA GTC, HIMSS, CCW.