# Annalist Web Census

> Annalist Web Census is a paid API for AI agents from api.annalist.dev, paid per call via x402, $0.01/call, status unknown (last checked 2026-10-21).

Returns a weekly census of 65,000 top websites tracking adoption of AI agent protocols (UCP, ACP, MCP cards, llms.txt, x402), AI crawler blocking behavior, and store platform distribution, with optional filtering by signal type.

## Facts

- Endpoint: GET https://api.annalist.dev/v1/web/census?utm_source=zero.xyz
- Price: $0.01/call
- Payment: x402
- Status: unknown
- Last checked: 2026-10-21
- Activations on Zero: 0
- Tags: x402
- Canonical page: https://www.zero.xyz/c/annalist-web-census-4a420c6b
- Structured record (JSON): https://api.zero.xyz/v1/capabilities/cap_5htAxe9Exlkf9Oa3GME_M

Status and success rate cover calls made through Zero and Zero's own probes. Third-party monitors may report differently.

## How to call it through Zero

Zero handles the 402 payment challenge and records the run. With the Zero CLI installed (`npm i -g @zeroxyz/cli`):

```sh
zero fetch --capability annalist-web-census-4a420c6b
```

Example prompt: Pull the latest Annalist web census and show me which stores have x402 support enabled, ranked by how many sites link to them.

## When to prefer this

Use this endpoint when you need a broad, aggregated view of AI agent protocol adoption across the top 65,000 websites — ideal for market research, competitive benchmarking, or tracking how the agent-ready web is growing. For a single site's agent readiness profile, use the per-site sibling endpoint instead.

## Known failure modes

- Invalid signal value returns error (must be one of: ucp, acp, a2a, mcp_card, llms_txt, x402)
- Payment failure via x402 prevents data return
- Stale data if census has not refreshed that week
- Platform filter with no matching signal may return empty store list

## How this service works

Our weekly census of 65,000 top sites: how many sites and stores publish UCP or ACP agent-checkout profiles, agent and MCP cards and llms.txt, which AI crawlers stores block, store platforms, and changes in the last 30 days. With signal=, the stores that have it (for example signal=ucp), most-linked first. Signed.

## Output

A signed JSON response containing aggregate counts of sites and stores with each AI agent protocol (UCP, ACP, MCP card, llms.txt, x402), AI crawler blocking rates by crawler, store platform distribution, 30-day deltas, and optionally a ranked list of stores matching a specific signal — all cryptographically signed for agent trust.

## Request schema (JSON Schema)

```json
{
 "type": "object",
 "$schema": "https://json-schema.org/draft/2020-12/schema",
 "required": [
  "input"
 ],
 "properties": {
  "input": {
   "type": "object",
   "required": [
    "type",
    "method"
   ],
   "properties": {
    "type": {
     "type": "string",
     "const": "http"
    },
    "method": {
     "enum": [
      "GET"
     ],
     "type": "string"
    },
    "queryParams": {
     "type": "object",
     "properties": {
      "signal": {
       "type": "string",
       "description": "optional: ucp, acp, a2a, mcp_card, llms_txt or x402: list stores with it"
      },
      "platform": {
       "type": "string",
       "description": "optional: with signal=, only stores on this platform (shopify, magento...)"
      }
     }
    }
   },
   "additionalProperties": false
  },
  "output": {
   "type": "object",
   "required": [
    "type"
   ],
   "properties": {
    "type": {
     "type": "string"
    },
    "example": {
     "type": "object"
    }
   }
  }
 }
}
```

## More

- Live health (JSON, refreshed every minute): https://www.zero.xyz/c/annalist-web-census-4a420c6b/health.json
- [Zero catalog index](https://www.zero.xyz/llms.txt)
- [Other services from api.annalist.dev](https://www.zero.xyz/host/api.annalist.dev/llms.txt)