What is SKU.md, and how do you use it?

SKU.md is an open Markdown file format published by merchants. Start with a catalog entry point for your store. Optionally add specifications, usage conditions and limitations, with sources. AI assistants (agents), search-engine crawlers and other tools that support SKU.md can follow the links to read the details and check their sources.

Quick Start Read Specification

Why SKU.md?

One small, merchant-owned file gives agents an official entry point to the public catalog without copying the catalog into a new system.

Optional per-item documents can add stable product facts when each fact is backed by a visible public source.

Stable knowledge stays separate from changing price, inventory, shipping, offer, and transaction state, which remain with live commerce systems.

Publishing SKU.md does not guarantee platform adoption, citation, ranking, recommendation, visibility, or sales.

Where do product details and live information belong?

Use each layer for the information it can truthfully own, and hand changing state to the live authority.

SKU.md · Catalog and product details

A catalog entry point and source-linked specifications, usage conditions and limitations.

Product page, Feed or Catalog · Current information

Check current prices, stock, delivery and availability.

Commerce systems · Purchases and orders

Handle carts, checkout, payments and orders.

A bounded responsibilities map

These surfaces complement one another. None is evidence that a platform has adopted SKU.md.

robots.txt

Crawl access

Expresses crawler access preferences; it is not a catalog, knowledge source, or transaction interface.

Sitemap

URL discovery

Lists site URLs and update hints for discovery; it does not describe product facts or live offers.

llms.txt

Curated document pointers

Points readers to selected site documents; it does not replace the merchant catalog or authorize transactions.

Product JSON-LD

Page-level structured data

Describes a product on an HTML page for structured-data consumers; freshness depends on that page.

Merchant Feed

Live products and offers

Carries platform-specific product, offer, price, availability, shipping, and market data.

WebMCP

Page-level interaction

Exposes bounded tools from a web page when supported; it does not make static knowledge live commerce authority.

MCP

Tool and resource access

Connects agents to declared tools and resources under the server's own permissions and freshness boundary.

UCP

Transaction coordination

Coordinates supported commerce capabilities and transaction state such as checkout and orders.

ACP

Agentic commerce transactions

Carries supported agentic commerce transaction exchanges under its own live contract and authority boundary.

Start with one catalog entry file

Include the store name, summary, website and catalog link. You can start before preparing details for every product.

These are reproducible rule tests, not model rankings or predictions of sales. Live information must be checked at the store.

# Example Outdoor Gear
> Lightweight outdoor equipment for hikers.

SKU.md: [1.0.0](https://sku.md/spec/1.0.0/)
Website: [example-outdoor.com](https://www.example-outdoor.com/)

## Catalog
- [All products](https://www.example-outdoor.com/collections/all)

From product page to reviewed product knowledge

Read a product page

Read a public product page and retain its source.

Check data

Check missing, conflicting, or unsupported attributes.

Check details and sources

Review each quotation before accepting a fact.

Compare selections

Compare products against explicit purchase conditions.

Download product details

Editable Markdown and suggested product-page structured data changes for human review.