# Hugen Tokyo x402 API Discovery Search

> Hugen Tokyo x402 API Discovery Search is a paid API for AI agents from discovery.hugen.tokyo, paid per call via x402, $0.005/call, status unknown (last checked 2026-09-15).

Search a catalog of 2,400 quality-scored x402 pay-per-call APIs across 24 categories, returning relevance-ranked results with pricing, network, and brokerable metadata

## Facts

- Endpoint: GET https://discovery.hugen.tokyo/discovery/search
- Price: $0.005/call
- Payment: x402
- Status: unknown
- Last checked: 2026-09-15
- Activations on Zero: 0
- Tags: x402
- Canonical page: https://www.zero.xyz/c/discovery-hugen-tokyo-8bef7bea
- Structured record (JSON): https://api.zero.xyz/v1/capabilities/cap_63ds_FzVzn0fmvrnzwS-K

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 discovery-hugen-tokyo-8bef7bea
```

Example prompt: Search the x402 API catalog for pay-per-call AI or LLM APIs available on Base — show me the top 10 results with their prices and quality scores.

## When to prefer this

Use this endpoint when an AI agent needs to discover which x402 pay-per-call APIs exist for a given capability or domain, especially when the agent needs to find APIs that accept USDC on Base or Solana and has no prior knowledge of available endpoints. Prefer this over general web search when you need structured, quality-scored, machine-readable API metadata.

## Known failure modes

- Empty results if query term matches no registered APIs
- Missing or malformed `q` parameter returns error
- Category filter typo returns empty set
- Rate limit or payment failure returns 402 or 429
- Stale entries if an API was deregistered after lastUpdated

## How this service works

Find x402 pay-per-call APIs — 2,400 verified entries across 24 categories (DeFi, Weather, AI/LLM, Security, Finance/FX, Content, Domain, Visual, Intelligence, etc). Quality-scored, relevance-ranked with brokerable flag. No setup needed. Accepts USDC payments on Base and Solana

## Output

A JSON array of up to `limit` API entries, each with: url, price, network (e.g. Base or Solana), category, brokerable boolean, description, lastUpdated timestamp, and quality_score. Results are ranked by relevance to the query.

## Example request

```json
{
 "q": "weather",
 "limit": 10,
 "category": "Weather"
}
```

## Request schema (JSON Schema)

```json
{
 "type": "object",
 "properties": {
  "q": {
   "type": "string",
   "title": "Q",
   "default": "",
   "description": "Search keywords (e.g. 'weather forecast', 'defi token security'). Empty = browse recent APIs across categories."
  },
  "limit": {
   "type": "integer",
   "title": "Limit",
   "default": 10,
   "maximum": 20,
   "minimum": 1,
   "description": "Max results (1-20)"
  },
  "category": {
   "type": "string",
   "title": "Category",
   "default": "",
   "description": "Category filter (e.g. 'DeFi', 'Weather', 'AI/LLM')"
  }
 }
}
```

## Response schema (JSON Schema)

```json
{
 "type": "object",
 "required": [
  "query",
  "results",
  "call_via",
  "total_results",
  "category_filter"
 ],
 "properties": {
  "query": {
   "type": "string"
  },
  "results": {
   "type": "array",
   "items": {
    "type": "object",
    "required": [
     "url",
     "price",
     "network",
     "category",
     "call_hint",
     "brokerable",
     "description",
     "lastUpdated",
     "quality_score"
    ],
    "properties": {
     "url": {
      "type": "string"
     },
     "price": {
      "type": "string"
     },
     "network": {
      "type": "string"
     },
     "category": {
      "type": "string"
     },
     "call_hint": {
      "type": "string"
     },
     "brokerable": {
      "type": "boolean"
     },
     "description": {
      "type": "string"
     },
     "lastUpdated": {
      "type": "string"
     },
     "quality_score": {
      "type": "number"
     }
    }
   }
  },
  "call_via": {
   "type": "object",
   "required": [
    "key",
    "sdk",
    "broker"
   ],
   "properties": {
    "key": {
     "type": "string"
    },
    "sdk": {
     "type": "string"
    },
    "broker": {
     "type": "string"
    }
   }
  },
  "total_results": {
   "type": "number"
  },
  "category_filter": {
   "type": "string"
  }
 }
}
```

## More

- Live health (JSON, refreshed every minute): https://www.zero.xyz/c/discovery-hugen-tokyo-8bef7bea/health.json
- [Zero catalog index](https://www.zero.xyz/llms.txt)
- [Other services from discovery.hugen.tokyo](https://www.zero.xyz/host/discovery.hugen.tokyo/llms.txt)