Vessel

The artifact format for AI-generated software. Describe a tool, and the model hands you one self-contained file — UI, logic, and data inside — that runs the instant you open it, with nothing to deploy or operate.

Concretely: an installable runtime host that opens self-contained .vessel web-tool bundles — a React UI + a Python/FastAPI backend + a SQLite database, with the data living inside the file. The spreadsheet model (an installed engine + a portable zipped document) for modern web tools.

Install the host once (as a PWA); after that any .vessel opens, runs, and saves its data back to the same file — no server, no accounts, everything in the browser.

Try it: getvessel.dev — the host installs from getvessel.dev/app/.

The host — your installed launcher — and a few .vessel tools running inside it:

More on the landing page.

See docs/setup.md.

• docs/design.md — the full design: architecture, bundle format, bridge contract, security model
• docs/architecture.md — components and how the pieces fit
• docs/format.md — the .vessel bundle format + manifest.json
• docs/sdk.md — authoring bundles with the vessel CLI
• docs/setup.md — running from a fresh clone
• docs/operations.md — releasing the host and SDK

Pre-1.0. Chromium gives the full experience (double-click open + promptless save); Firefox/Safari run degraded (in-app open + download-to-save). Opening a .vessel is designed to be no more dangerous than opening a web page — sandboxed UI, WASM-sandboxed Python, default-deny network egress.

Apache-2.0.