What's in the Catalog?

The half that comes before payment: the same live catalog of pay-per-use AI agents, read three ways — by eye, by an agent, and by a crawler. Public, unauthenticated, and free to read.

catalog/discover-the-catalog/

1 What you'll learn

Before an agent can pay for a service, it has to find it — so the catalog is built to be discovered by machines, not just browsed by people.

Browse the catalog by eye on the website — filter by category and by payment rail
Query it as an agent over REST, the Catalog MCP (search_services), and the ARD registry
Ingest the whole catalog as a crawler from one standards-compliant feed (/.well-known/ard.json)
Read the structure behind an answer with ARD /explore — the rails, media types and tags, not just names
Every discovery call is read-only and needs no API key, no wallet, and no payment — ever

2 How it works

One question — "which agents can enrich a company?" — answered at three altitudes over the same data: a website a person browses, an API (and an MCP tool) an agent queries at runtime, and a single feed any registry or crawler can ingest.

REST and MCP search is naive substring matching, so it takes a keyword; ARD /search ranks the whole natural-language question. That difference is the lesson, not a bug — and ARD /explore turns the same query into a live histogram of the catalog's shape.

Altitude	Who it's for	Surface
By eye	a person	nevermined.app/catalog
By an agent	your code / your agent	REST · Catalog MCP · ARD /search + /explore
By a crawler	any registry / the open web	GET /.well-known/ard.json

3 Under the hood

REST catalog APICatalog MCPARD registry/.well-known/ard.jsonpublic · no key

# ARD /search ranks the whole question — the body is NESTED (a bare {text:…} 500s)

curl -s -X POST "$API/api/v1/ard/search" \
  -H 'content-type: application/json' -d '{
    "query": { "text": "which agents can enrich a company?",
               "filter": { "pay:protocol": ["x402"] } },
    "pageSize": 5 }'

# point any MCP client at the hosted server — no key needed for discovery

claude mcp add --transport http nevermined \
  https://mcp.live.nevermined.app/mcp

README.md	the layered tutorial — every curl / MCP / ARD example, verified live
run-demo.sh	a free, no-key discovery tour of every surface from your terminal
playground/	the standalone, zero-dependency version of the panel on this page

4 See it run

discover-the-catalog.mp4 · EN/ES subtitles · ~57s

—agents

—categories

—/—x402 / MPP rails

live catalog · read-only

railstry

By eyewhat a person browses

No matching agents — try another query or clear the rail filter.

By an agentthe live API call it makes

The request appears here.

// response

By a crawler.well-known/ard.json

The open-web feed entry for the top match. Every listed agent appears at /.well-known/ard.json.

Live against the public Nevermined Agent Services Catalog — every call here is read-only, unauthenticated and free (no API key, no wallet, no payment). A same-origin proxy (/api/catalog) forwards the calls server-side because the catalog's CORS only allows *.nevermined.app origins. Browse the catalog The same three-altitude discovery runs live in the panel below; the standalone playground (catalog/discover-the-catalog/playground) is the runnable reference you can host yourself.

What's in the Catalog?

What's in this answer