# Underground Cultural District Catalog

> Underground Cultural District Catalog is a paid API for AI agents from underground.substratesymposium.com, paid per call via x402, $0.01/call, status unknown (last checked 2026-09-15).

Returns the full catalog of 228 themed digital products (poetry, philosophy, fiction, reflections, plant meditations) with slugs, descriptions, prices, and x402 purchase endpoints

## Facts

- Endpoint: GET https://underground.substratesymposium.com/buy/catalog
- Price: $0.01/call
- Payment: x402
- Status: unknown
- Last checked: 2026-09-15
- Activations on Zero: 0
- Tags: x402
- Canonical page: https://www.zero.xyz/c/underground-substratesymposium-com-a89d203d
- Structured record (JSON): https://api.zero.xyz/v1/capabilities/cap_qeytzRkbWOpi8wMCLiv20

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 underground-substratesymposium-com-a89d203d
```

Example prompt: Show me the full catalog of digital products available in the Underground Cultural District — I want to see all the poetry, philosophy, fiction, and plant meditations with their prices and how to buy each one.

## When to prefer this

Use this endpoint when you need to discover what digital content products are available for purchase before buying individual items — it serves as the single entry point to find all 228 products and their individual x402 purchase routes, making it the required first step for any browsing or purchasing workflow on this platform

## Known failure modes

- 402 Payment Required if the $0.01 USDC payment is not settled before the request
- Network or server errors returning 5xx if the catalog service is unavailable
- Truncated or partial catalog response if the response is too large (catalog is ~10KB+)
- Empty or stale catalog if products have been removed or the index has not been updated

## How this service works

Underground Cultural District — catalog of 228 themed digital products (poetry, philosophy, fiction, reflection, plant meditations). One settle returns the full menu with every product's slug, description, price, and x402 endpoint. Each individual product is its own indexable x402 route. The catalog is the doorway.

## Output

A full catalog listing of all 228 themed digital products, each with its slug, description, price (in USDC), and the individual x402 endpoint URL to purchase that specific product

## Example request

```json
{
 "query": "{\\\"input\\\": {\\\"type\\\": \\\"http\\\", \\\"method\\\": \\\"GET\\\", \\\"queryParams\\\": {}}}"
}
```

## 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": {}
    }
   },
   "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/underground-substratesymposium-com-a89d203d/health.json
- [Zero catalog index](https://www.zero.xyz/llms.txt)
- [Other services from underground.substratesymposium.com](https://www.zero.xyz/host/underground.substratesymposium.com/llms.txt)