# Show HN: KaliCart – an agent-readable catalog for WooCommerce (no API key) > Source: > Published: 2026-06-29 16:08:24+00:00 Free WooCommerce plugin that makes your product catalog machine-readable for AI shopping agents. ARC/1.0 reference implementation · No LLM · No cloud · No API key When an AI shopping agent visits a WooCommerce store today, its default behavior is to fetch the storefront HTML and scrape product data from it. This is the wrong approach — and in a documented blind test on a live store, the cost was measurable: | Approach | API calls | Payload | Stock accuracy | Color filtering | |---|---|---|---|---| | HTML scraping | 5–6 | ~400 KB | High (dropdowns show real variants) | Manual, from text | WordPress REST (`wp/v2/product` ) | 2 | ~77 KB (truncated) | Low — `class_list` reports defined sizes, not in-stock ones | None | KaliCart Bridge (ARC/1.0) | 2 | ~4–5 KB (≈10 KB incl. discovery) | High — per-variant quantity with confidence level | Native `color=` filter | *Blind test: finding a dark-colored women's two-piece swimsuit, size S, under €150, on a live WooCommerce store. The agent was given no hints. It scraped HTML first, then tried the generic WordPress REST API (which produced a false positive on stock), and found the structured kalicart/v1 catalog only when explicitly pointed at it — even though that namespace was reachable from /wp-json the whole time. See * [BENCHMARK.md](/giuseppesocci-bot/kalicart-bridge/blob/main/BENCHMARK.md)for the full run, including honest caveats (n=1, discovery cost). **The signal to do better has always been there.** Every WordPress site already emits `` in the HTML `` . An agent that reads the head before scraping finds the REST API namespace in one call, discovers `kalicart/v1` , and filters natively. KaliCart Bridge makes that path correct and complete. KaliCart Bridge installs on any WooCommerce store and exposes five things: - **A discovery document**(`/wp-json/kalicart/v1/discovery` ) — a self-describing JSON contract that tells an agent everything it needs: all endpoint URLs, accepted filters, shipping policy, coupon rules, agent instructions. One GET, no documentation required. - **A computable catalog**— structured REST endpoints for search, product listing, categories, and per-product detail including live stock per variant, price encoding declaration, purchase readiness, and shipping eligibility. - **Agent discovery signals**—`` in the storefront`` ,`.well-known/kalicart-bridge.json` ,`.well-known/agent-catalog.json` ,`robots.txt` entries, and an agentic sitemap — so agents that land on the storefront can find the API without scraping. - **UCP interoperability**—`/.well-known/ucp.json` declares`catalog.search` and`catalog.lookup` capabilities for UCP-compliant agents (ChatGPT, Copilot, Gemini). - **Federated catalog opt-in**— one toggle publishes eligible products into[KaliCart Global](https://global.kalicart.com), a read-only multi-merchant index that AI agents can query across stores without knowing any individual merchant in advance. ``` AI agent │ ├─ 1. GET global.kalicart.com/v1/global-catalog/search?q=... ← find merchants + products │ (federated index — optional first step) │ ├─ 2. GET {merchant}/wp-json/kalicart/v1/discovery ← read contract │ ├─ 3. GET {merchant}/wp-json/kalicart/v1/catalog/search ← native filters │ ?q=bikini&color=purple&in_stock=true&max_price=150 │ └─ 4. GET {merchant}/wp-json/kalicart/v1/catalog/product/{id} ← verify variants + stock → per-variant quantity, shipping eligibility, purchase readiness │ └─ Checkout always on merchant storefront (KaliCart never processes payments) ``` **Three layers of authority:** **KaliCart Global**— discovery and routing across the federated network** Merchant bridge**— authoritative price, live stock, variant detail** Merchant storefront**— sole authority for checkout and payment - Download or install from`kalicart-bridge-latest.zip` [WordPress.org](https://wordpress.org/plugins/kalicart-bridge/) - Upload and activate from **WP Admin → Plugins → Add New → Upload** - WooCommerce must be active - All discovery signals are injected automatically on activation - Visit **WP Admin → KaliCart** for the catalog health dashboard That's it. Your catalog is now machine-readable. Every ARC-compliant storefront emits this tag: ``` ``` **Read the before scraping.** This single tag gives you the discovery document URL directly. ``` GET https://shop.example.com/wp-json/kalicart/v1/discovery ``` The discovery document is a self-describing contract. It contains: - All endpoint URLs - Accepted filter values (categories, colors, genders, price range) - Shipping policy - Coupon rules `agent_instructions` — ordered steps for correct query construction`result_guidance` — embedded in every response, tells you what to do next ``` GET /wp-json/kalicart/v1/catalog/search ?category=donna-beachwear-resortwear-bikini &color=purple &in_stock=true &max_price=150 ``` **Critical rule:** `q` must contain only the bare product noun. Every attribute (color, gender, size, price) must go in its own filter — never stacked into `q` . ``` ✓ correct GET /catalog/search?q=bikini&color=black&gender=female&max_price=150&in_stock=true ✗ wrong — zero results GET /catalog/search?q=black+women+bikini+under+150 ``` Search responses return product-level stock. For variable products (size, color variants), fetch the detail endpoint to get per-variant quantities: ``` GET /wp-json/kalicart/v1/catalog/product/{id} ``` Response includes: ``` { "variants": [ { "attributes": { "pa_taglia": "s" }, "stock": { "in_stock": true, "quantity": 1, "confidence": "numeric_stock_quantity", "agent_note": "Last unit available. Race condition possible — complete checkout immediately." } } ], "shipping": { "free_shipping_available": true, "free_shipping_eligible_by_product_price": true } } ``` To find products without knowing the merchant in advance: ``` GET https://global.kalicart.com/v1/global-catalog/search ?q=bikini&color=purple&gender=female&price_max=150&availability=in_stock ``` Results include `merchant_id` and a link to the merchant's bridge for authoritative verification. Every KaliCart Bridge response includes a `result_guidance` field that tells the agent how to proceed: ``` { "result_guidance": { "code": "SUMMARY_TRIAGE", "next_step": "rank_from_summary_then_verify_one_selected_product", "fact_coverage": { "complete_for": ["product_identity", "catalog_price", "availability_status"], "detail_required_for": ["exact_variants_or_sizes", "stock_precision_beyond_status"] }, "detail_fetch_policy": { "verification_url_template": "https://shop.example.com/wp-json/kalicart/v1/catalog/product/{id}" } } } ``` This means agents do not need external documentation to know what to do next. The API tells them. KaliCart Bridge is the reference implementation of ** ARC/1.0 — Agent-Readable Catalog**, an open specification (CC BY 4.0) for exposing e-commerce catalogs as agent-consumable REST surfaces. ARC/1.0 defines: - Three discovery signals (HTML head link, `.well-known/` ,`robots.txt` ) - The discovery document contract - Catalog endpoint requirements - The product object schema (price encoding, stock confidence levels, variant contract) - Consent model for federated indexing - UCP interoperability - Security rules (read-only, no API keys on public surfaces) Any e-commerce platform can implement ARC/1.0. KaliCart Bridge does it for WooCommerce. Every AI agent that scrapes instead of using a structured catalog wastes: **~40× more data per task**(~400 KB scraped vs ~10 KB end-to-end including discovery, in the documented test)** More API calls**(5–6 vs 2 for the catalog calls)** LLM tokens**parsing irrelevant HTML boilerplate** Latency**on every user-facing query The data returned by scraping the generic WordPress REST API is also less accurate: HTML dropdowns show truly available variants, but the `wp/v2` `class_list` field reports all defined sizes regardless of current stock. In the documented test, an agent trusting `class_list` would have reported a size as available when it was sold out. As agentic commerce grows, the aggregate cost of the scraping default — compute, latency, and wrong answers handed to shoppers — becomes significant and avoidable. ARC/1.0 and KaliCart Bridge exist to change that default. **Plugin hub & download**:[bridge.kalicart.com](https://bridge.kalicart.com)** ARC/1.0 specification**:[bridge.kalicart.com/spec](https://bridge.kalicart.com/spec/)** Documentation**:[bridge.kalicart.com/docs](https://bridge.kalicart.com/docs/)** Federated catalog**:[global.kalicart.com](https://global.kalicart.com)** WordPress MCP plugin**:[mcp.kalicart.com](https://mcp.kalicart.com)** Institutional**:[kalicart.com](https://kalicart.com)** WordPress.org**:[wordpress.org/plugins/kalicart-bridge](https://wordpress.org/plugins/kalicart-bridge/) Plugin code: [GPLv2](https://www.gnu.org/licenses/gpl-2.0) ARC/1.0 specification text: [CC BY 4.0](https://creativecommons.org/licenses/by/4.0/) © 2026 Save The Brain