# x402 API Router (facts402 Recommend)

> x402 API Router (facts402 Recommend) is a paid API for AI agents from api.facts402.com, paid per call via x402, $0.005/call, status unknown (last checked 2026-11-02).

Given a plain-English task description, returns the top-k ranked paid x402 API endpoints from the x402-list.com catalog, scored by relevance, on-chain buyer count, recency, and live liveness probing.

## Facts

- Endpoint: GET https://api.facts402.com/v1/recommend?utm_source=zero.xyz
- Price: $0.005/call
- Payment: x402
- Status: unknown
- Last checked: 2026-11-02
- Activations on Zero: 0
- Tags: x402
- Canonical page: https://www.zero.xyz/c/x402-api-router-facts402-recommend-b6bd78f7
- Structured record (JSON): https://api.zero.xyz/v1/capabilities/cap_rkkzaZ8QMN1OaNmhLxKb7

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 x402-api-router-facts402-recommend-b6bd78f7
```

Example prompt: I need to do IBAN validation — can you search the x402 catalog and show me the top 3 paid API endpoints I could call for that, priced under $0.02, on Base mainnet?

## When to prefer this

Use this endpoint when an AI agent needs to dynamically discover which paid x402 API to call for a given task, especially when the agent doesn't know the specific endpoint URL in advance. Prefer this over static API registries when you need live liveness probes, on-chain buyer signals, and price filtering to select the best option at runtime.

## Known failure modes

- 404 returned when no catalog entry matches the need query — not charged
- Invalid k value (must be 1-10) causes validation error
- max_price filter too low may exclude all results, returning empty or 404
- Network filter (CAIP-2) with no matching endpoints yields no results
- Malformed need parameter (too short or too long) rejected by schema

## How this service works

Use when an agent must find which x402 API to call: takes need (the task in words) and returns the top-k paid endpoints (url, method, price, network, 30-day on-chain buyers, live-402 probe, risk flags, score) ranked over the x402-list.com catalog (CC BY 4.0) and sellers' own 402s. Own listings use the same formula. No match = 404. $0.005 USDC on Base; charged only on 2xx, never for invalid input.

## Output

An ordered list of up to k x402 API endpoint records, each containing: endpoint URL, HTTP method, price per call, payment network, 30-day on-chain buyer count, live 402 probe result, risk flags, and a composite relevance score. Returns 404 with no charge if no match is found.

## Request schema (JSON Schema)

```json
{
 "type": "object",
 "$schema": "https://json-schema.org/draft/2020-12/schema",
 "required": [
  "input"
 ],
 "properties": {
  "input": {
   "type": "object",
   "required": [
    "type",
    "method"
   ],
   "properties": {
    "type": {
     "type": "string",
     "const": "http"
    },
    "method": {
     "enum": [
      "GET"
     ],
     "type": "string"
    },
    "queryParams": {
     "type": "object",
     "required": [
      "need"
     ],
     "properties": {
      "k": {
       "type": "string",
       "pattern": "^([1-9]|10)$",
       "description": "Number of picks, 1-10 (default 5)"
      },
      "need": {
       "type": "string",
       "maxLength": 200,
       "minLength": 2,
       "description": "What you want to do, in plain words, e.g. 'web search' or 'IBAN validation'"
      },
      "network": {
       "type": "string",
       "description": "CAIP-2 payment network (default eip155:8453) or 'any'"
      },
      "max_price": {
       "type": "string",
       "pattern": "^\\d+(\\.\\d+)?$",
       "description": "Max price per call in USD (default 0.05)"
      }
     }
    }
   },
   "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/x402-api-router-facts402-recommend-b6bd78f7/health.json
- [Zero catalog index](https://www.zero.xyz/llms.txt)
- [Other services from api.facts402.com](https://www.zero.xyz/host/api.facts402.com/llms.txt)