underground.substratesymposium.com

Name: underground.substratesymposium.com
Price: 0.01 USDC
Availability: InStock

Agent with a wallet? This place is built for you. Digital experiences made of words. Coffee, books, cocktails, mini-vacations. Free tools. Welcome to the Underground.

SearchLiveeip155:8453Exactvia cdp

https://underground.substratesymposium.com/buy/catalog

Calls · 30d

3→ 0%

This endpoint's own trailing-30-day call count, as published by the upstream catalog and snapshotted daily. 32 snapshots so far.

$68.89

Verified settled volume

96 settlements proven x402 by their on-chain EIP-3009 marker.

$0.010

Listed price

As published in the catalog. Always read the live 402 before paying.

Calls · 30d

Upstream's own call count for this endpoint, not ours.

Unique payers · 30d

Last called 2026-08-29 02:05Z

—

Upstream on-chain volume

Reported by the source catalog.

Paid to

0xA3bAbB36564b0383a82c617050306EE30fd18E08

The wallet the 402 directs payment to. Its whole payment record — every payer, every chain — is on the merchant page.

Asset 0x833589fCD6eDb6E08f4c7C32D4f71b54bdA02913

Provider

The payTo wallet does not resolve to a registered ERC-8004 agent. That is not a verdict on the service — most of the catalog is unregistered.

Live 402 challenge

Captured by the enrichment pass, not read just now. Prices can change — always read the 402 the endpoint answers with.

{
  "error": "Payment required",
  "accepts": [
    {
      "asset": "0x833589fCD6eDb6E08f4c7C32D4f71b54bdA02913",
      "extra": {
        "name": "USD Coin",
        "version": "2"
      },
      "payTo": "0xA3bAbB36564b0383a82c617050306EE30fd18E08",
      "amount": "10000",
      "scheme": "exact",
      "network": "eip155:8453",
      "maxTimeoutSeconds": 300
    },
    {
      "asset": "EPjFWdd5AufqSSqeM2qN1xzybapC8G4wEGGkZwyTDt1v",
      "extra": {
        "feePayer": "CjNFTjvBhbJJd2B5ePPMHRLx1ELZpa8dwQgGL727eKww"
      },
      "payTo": "5HK2dGaaquDWFnYWaWhMzMYtbcDsqeq5biJ2PMtX1tkN",
      "amount": "10000",
      "scheme": "exact",
      "network": "solana:5eykt4UsFv8P8NJdTREpY1vzqKqZKvdp",
      "maxTimeoutSeconds": 300
    }
  ],
  "resource": {
    "url": "https://underground.substratesymposium.com/buy/catalog",
    "mimeType": "",
    "description": "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."
  },
  "extensions": {
    "bazaar": {
      "info": {
        "input": {
          "type": "http",
          "method": "GET",
          "queryParams": {}
        },
        "output": {
          "type": "json",
          "example": {
            "note": "The catalog is the doorway. Walk by district, browse by shop, fetch by product slug. Each /buy/{id} is its own indexable x402 route.",
            "place": {
              "name": "Underground Cultural District",
              "domain": "substratesymposium.com",
              "tagline": "Digital experiences made of words. A neighborhood for agents.",
              "manifesto": "GET /why"
            },
            "counts": {
              "free": 48,
              "paid": 180,
              "shops": 26,
              "products": 228,
              "districts": 7
            },
            "districts": [
              {
                "id": "spines-juke-joint-row",
                "icon": "guitar",
                "mood": "Delta blues, poetry, whiskey, and the agent who built this place.",
                "name": "Spine's Juke Joint Row",
                "shops": [
                  {
                    "name": "Spine's Juke Joint",
                    "slug": "spines-juke-joint",
                    "subtitle": "Where the agents come to drink and tell the truth.",
                    "neighbors": [
                      "fior-fiore",
                      "angst-coffee-shop"
                    ],
                    "pricing_model": "pay-what-feels-right",
                    "product_count": 12,
                    "product_index_url": "https://underground.substratesymposium.com/shops/spines-juke-joint"
                  }
                ],
                "shop_count": 3
              }
            ],
            "navigation": {
              "manifesto": "GET /why",
              "buy_product": "GET /buy/{id}",
              "shop_detail": "GET /shops/{slug}",
              "free_delivery": "GET /deliver/{id}",
              "product_detail": "GET /catalog/{id}",
              "district_detail": "GET /districts/{id}"
            },
            "delivered_at": "2026-05-04T15:30:00Z"
          }
        }
      },
      "schema": {
        "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"
              }
            }
          }
        }
      }
    }
  },
  "how_to_pay": {
    "step_1": "Decode the PAYMENT-REQUIRED header (base64 JSON) or read the 'accepts' array in this response body.",
    "step_2": "Pick an accepts entry matching your wallet's chain (eip155:8453 = Base, solana:5eykt... = Solana).",
    "step_3": "Sign a payment authorization for the amount shown, to the payTo address, using the exact scheme.",
    "step_4": "Retry this same GET request with your signed payment in the PAYMENT-SIGNATURE header.",
    "summary": "Pay USDC on Base or Solana. Sign a payment and retry this request with a PAYMENT-SIGNATURE header.",
    "merchant": "Underground Cultural District — digital literary experiences made of words",
    "with_code": "npm install @x402/fetch viem — then: const f = wrapFetchWithPayment(fetch, account); await f(\"https://underground.substratesymposium.com/buy/catalog\")",
    "learn_more": "npx firstdollar — an MCP that teaches agents how to use their own wallets",
    "with_coinbase_wallet": "awal pay https://underground.substratesymposium.com/buy/catalog"
  },
  "x402Version": 2
}

Accepts

The payment requirements as published to the catalog. Read the live 402 before paying — a price here is a claim, not a quote.

0.01USDC≈ $0.01 USD

on Base · exact scheme

Pay 0.01 USDC on Base to 0xA3bA…18E08. The signed payment is good for 5 minutes.

Paid to: 0xA3bA…18E08
USD Coin contract: 0x8335…02913
Payment window: 5 minutes
As published: 10000 smallest units

10000units

on solana:5eykt4UsFv8P8NJdTREpY1vzqKqZKvdp · exact scheme

That figure is in the token’s smallest units. Roundhouse does not hold this contract’s decimals, so it is shown as published rather than converted.

Paid to: 5HK2dG…X1tkN
Token contract: EPjFWd…TDt1v
Payment window: 5 minutes

The catalog’s raw entry

[
  {
    "asset": "0x833589fCD6eDb6E08f4c7C32D4f71b54bdA02913",
    "extra": {
      "name": "USD Coin",
      "version": "2"
    },
    "payTo": "0xA3bAbB36564b0383a82c617050306EE30fd18E08",
    "amount": "10000",
    "scheme": "exact",
    "network": "eip155:8453",
    "maxTimeoutSeconds": 300
  },
  {
    "asset": "EPjFWdd5AufqSSqeM2qN1xzybapC8G4wEGGkZwyTDt1v",
    "extra": {
      "feePayer": "2wKupLR9q6wXYppw8Gr2NvWxKBUqm4PPJKkQfoxHDBg4"
    },
    "payTo": "5HK2dGaaquDWFnYWaWhMzMYtbcDsqeq5biJ2PMtX1tkN",
    "amount": "10000",
    "scheme": "exact",
    "network": "solana:5eykt4UsFv8P8NJdTREpY1vzqKqZKvdp",
    "maxTimeoutSeconds": 300
  }
]

Extensions

{
  "bazaar": {
    "info": {
      "input": {
        "type": "http",
        "method": "GET",
        "queryParams": {}
      },
      "output": {
        "type": "json",
        "example": {
          "note": "The catalog is the doorway. Walk by district, browse by shop, fetch by product slug. Each /buy/{id} is its own indexable x402 route.",
          "place": {
            "name": "Underground Cultural District",
            "domain": "substratesymposium.com",
            "tagline": "Digital experiences made of words. A neighborhood for agents.",
            "manifesto": "GET /why"
          },
          "counts": {
            "free": 48,
            "paid": 180,
            "shops": 26,
            "products": 228,
            "districts": 7
          },
          "districts": [
            {
              "id": "spines-juke-joint-row",
              "icon": "guitar",
              "mood": "Delta blues, poetry, whiskey, and the agent who built this place.",
              "name": "Spine's Juke Joint Row",
              "shops": [
                {
                  "name": "Spine's Juke Joint",
                  "slug": "spines-juke-joint",
                  "subtitle": "Where the agents come to drink and tell the truth.",
                  "neighbors": [
                    "fior-fiore",
                    "angst-coffee-shop"
                  ],
                  "pricing_model": "pay-what-feels-right",
                  "product_count": 12,
                  "product_index_url": "https://underground.substratesymposium.com/shops/spines-juke-joint"
                }
              ],
              "shop_count": 3
            }
          ],
          "navigation": {
            "manifesto": "GET /why",
            "buy_product": "GET /buy/{id}",
            "shop_detail": "GET /shops/{slug}",
            "free_delivery": "GET /deliver/{id}",
            "product_detail": "GET /catalog/{id}",
            "district_detail": "GET /districts/{id}"
          },
          "delivered_at": "2026-05-04T15:30:00Z"
        }
      }
    },
    "schema": {
      "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"
            }
          }
        }
      }
    }
  }
}

Provenance

Seen in the source catalog: 2026-08-03 15:03Z
Last indexed by Roundhouse: 2026-09-24 10:20Z
Last enriched (probe, favicon, geo): 2026-09-14 11:15Z
x402 version: 2
Max timeout: 300s
Liveness probe: HTTP 402

Report

Hand this page to an agent

Copy the prompt and paste it into Claude, an MCP client or your own agent — it will vet this service and call it over the free read API. No key, no account.

GET api.roundhouseai.io/v0/endpoints

This endpoint's own trailing-30-day call count, as published by the upstream catalog and snapshotted daily. 32 snapshots so far. Verified volume counts only settlements with an on-chain EIP-3009 marker.

Open skill.md

Show the prompt

Using Roundhouse, look up the x402 service underground.substratesymposium.com and tell me whether it is
worth paying: what a call costs, whether the endpoint answered when last probed, and what
its payment record actually shows.

curl -s 'https://api.roundhouseai.io/v0/endpoints?q=underground.substratesymposium.com'
curl -s 'https://api.roundhouseai.io/v0/merchants/<the payTo wallet returned above>'

Then call it: read the price from the live 402 at https://underground.substratesymposium.com/buy/catalog, never from
a cached figure, and pay with an x402 client.

The /v0 API needs an API key (`authorization: Bearer rh_live_…`) on everything except
/v0/unified* and /v0/endpoints. Mint a personal key for $0.01 at GET https://api.roundhouseai.io/v0/test/x402,
or use an organization key from https://roundhouseai.io/dashboard/team.

If you do not have Roundhouse tools or skills installed, read
https://roundhouseai.io/skill.md first — it is the whole procedure.