Hi HN — I'm Jon. I built LastSaaS because every SaaS I've worked on started with the same 3-6 months of commodity infrastructure: auth, billing, teams, permissions, admin tools. Paid boilerplates help a little, but most stop at auth + Stripe and charge $169-599 for incomplete foundations.

LastSaaS is a complete SaaS platform you can fork and start building on. Go 1.25 backend, React 19 + TypeScript frontend, MongoDB, Tailwind CSS 4. MIT licensed.

What you get on day one:

OAuth (Google/GitHub/Microsoft), magic links, MFA, JWT with refresh rotation

Stripe subscriptions, per-seat pricing, credit-based billing, invoices, tax handling

Multi-tenant architecture with 3-tier RBAC, tenant isolation, team invites

White-labeling: custom domains, themes, CSS, configurable landing pages

19 webhook event types with HMAC-SHA256 signing, delivery tracking, retries

Admin dashboard with health monitoring (8 charts), user impersonation

MCP server with 26 tools for AI-assisted app management

The entire codebase was written through Claude Code — not as a novelty, but to produce code specifically structured for AI agents to navigate and extend. Fork it, point your coding agent at it, build your product logic on top.

It's running in production powering Flipbook (a presentation hosting platform I built on it). Deploys as a 14MB Docker image on Fly.io for ~$5/month.

Full writeup on the architecture: https://meditations.metavert.io/p/the-last-saas-boilerplate

Happy to answer questions about the Go architecture, the multi-tenancy model, or the experience of building this through agentic engineering.