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.cart — an open standard for ecommerce carts

Status: v0.1 draft proposal. Feedback and pull requests welcome.

.cart is a proposed open file format (JSON, UTF-8) for describing the contents of an ecommerce shopping cart — the merchant, the line items, prices before and after VAT, shipping options, and the total awaiting payment — in a single portable, vendor-neutral file.

It is designed for agentic AI interoperability from the ground up: an agent or MCP server should be able to export a cart from any vendor into a .cart file, then import, compare, re-price, or transform it — for example into a purchase order or request for quotation (RFQ).

Start here

- :material-file-document: **[The specification](spec.md)** Every field, convention, and semantic in v0.1 — including the Core vs Expanded profiles. - :material-table: **[Data dictionary](reference/data-dictionary.md)** Every field in one flat table — path, type, required, profile, and PII sensitivity. Also as [JSON](downloads/data-dictionary.json) / [CSV](downloads/data-dictionary.csv). - :material-code-json: **[JSON Schema](schema.md)** Draft 2020-12 schema for validating `.cart` files. - :material-truck-delivery: **[Incoterms® 2020](reference/incoterms-2020.md)** The 11 delivery-terms rules used by `shipping.incoterms`. - :material-swap-horizontal: **[PO / RFQ standards mapping](reference/standards-mapping.md)** How `.cart` maps onto OASIS UBL, UN/CEFACT, and PEPPOL business documents.

Download the full spec

Grab the typeset specification PDF, the JSON Schema, and the machine-readable data dictionary (JSON / CSV) from the Downloads page.

What it's for

  • B2C — save a cart, move it between devices, share it, price-watch it.
  • B2B purchasing & procurement — capture carts as quote snapshots, compare suppliers on identical BOMs, and generate purchase orders and RFQs from carts.
  • Agentic tooling — MCP servers and browser agents that export, import, compare, and transform carts as first-class operations.

The idea

With agentic AI, carts no longer need to be trapped in browser sessions. A browser-based agent or an MCP server can already read any cart page — what's missing is a standard format to write it to. That's what .cart is.

Rather than invent new document formats for the downstream artifacts, .cart transformations map onto existing open standards — OASIS UBL and UN/CEFACT for the PO/RFQ documents, and ICC Incoterms® for delivery terms. See the standards mapping.

Source, issues, and contribution guide: github.com/danielrosehill/Dot-Cart · MIT licensed.