The Last SaaS

The Last SaaS is an open-source experiment by Mike Lay that identifies the primitives a minimal SaaS backend needs and exposes them to AI assistants and agents through MCP, a CLI, and an HTTP API. A hosted version is available, and the project can also be self-hosted under the MIT license.

The backend is written in TypeScript, runs on Bun, and supports SQLite (mostly for development and evaluation) and PostgreSQL (preferred).

What It Is

The Last SaaS is a headless backend rather than a finished application. It provides records, files, accounts, permissions, notifications, and audit logs, and lets assistants such as Claude, ChatGPT, Codex, Claude Code, Cursor, and Gemini CLI build on top of them. The homepage describes it as an experiment in finding the primitives all SaaS apps need.

The Primitives

• Records: collections with typed fields (text, number, date, and others) that are validated on save. Assistants can change fields, filter and sort records, and compute counts, totals, or averages.
• Files: upload and download files organized by path, with name, type, size, upload date, and uploader retained.
• Accounts: invite teammates as members or administrators, change roles, cancel pending invitations, and remove access. Each person can connect an assistant that acts through their account.
• Permissions: read, write, delete, and manage rules per user or role, with record and field restrictions that also apply when an assistant acts for the user.
• Notifications: immediate, scheduled, or recurring messages with email delivery, in-workspace retention, and user delivery preferences.
• Audit logs: a filterable history of record edits, file uploads, membership changes, and permission updates, with the responsible account and a timestamp.

Connecting an Assistant

After creating an account and an organization in the web app, users connect an assistant over MCP (for example, a custom connector pointed at the hosted MCP server URL) or through the saas CLI for tools with local terminal access. A guided tutorial is started by asking the connected assistant to walk through the getting-started tutorial.

Self-Hosting and Development

The repository is a monorepo containing the server (HTTP API, MCP, authentication, storage, and background jobs), the CLI client, and shared types. Local development requires Bun 1.2 or later. Builds produce a CLI binary and a server binary, with separate server builds for SQLite and PostgreSQL. Password authentication can be disabled, leaving Google (when configured) and magic-link sign-in. The server includes a bounded in-memory metadata cache for collection definitions and permission rules, intended for single-process deployments. The homepage says data can be exported with one command.

Current Status

The latest listed GitHub release is v0.1.0, published 2026-08-20.