Roundhouse

api.carbon-cashmere.de

Get real-time gas prices — Ethereum slow/standard/fast in gwei with base fee, Bitcoin fee estimates in sat/vB with mempool stats. AI agent API for transaction cost optimization, gas fee monitoring, and optimal execution timing.

TradingLiveeip155:8453Exactvia cdp
https://api.carbon-cashmere.de/v1/gas
Settlements · 30d
33↓ 86%
No per-endpoint history for this service yet, so this is payments indexed to its PROVIDER's wallet over 30 days.
$4.42
Verified settled volume
143 settlements proven x402 by their on-chain EIP-3009 marker.
$0.0050
Listed price
As published in the catalog. Always read the live 402 before paying.
1
Calls · 30d
Upstream's own call count for this endpoint, not ours.
1
Unique payers · 30d
Last called 2026-05-22 02:20Z
—
Upstream on-chain volume
Reported by the source catalog.
Paid to
0xf8b2dD46542175AD46e14e6133340E652665F2Ee

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.

Accepts

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

0.005USDC≈ $0.005 USD
on Base · exact scheme

Pay 0.005 USDC on Base to 0xf8b2…5F2Ee. The signed payment is good for 5 minutes.

Paid to
0xf8b2…5F2Ee
USD Coin contract
0x8335…02913
Payment window
5 minutes
As published
5000 smallest units
5000units
on Polygon · 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
0xf8b2…5F2Ee
Token contract
0x3c49…c3359
Payment window
5 minutes
5000units
on Arbitrum · 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
0xf8b2…5F2Ee
Token contract
0xaf88…e5831
Payment window
5 minutes
5000units
on eip155:480 · 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
0xf8b2…5F2Ee
Token contract
0x79A0…D24d1
Payment window
5 minutes
5000units
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
GgS891…rpCiD
Token contract
EPjFWd…TDt1v
Payment window
5 minutes
5000units
on algorand:wGHE2Pwdvd7S12BL5FaOP20EGYesN73ktiC1qzkkit8= · 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
5GRGZV…RGJGI
Token contract
31566704
Payment window
5 minutes
50000units
on stellar:pubnet · 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
GDYFWC…RO2VP
Token contract
USDC:G…4KZVN
Payment window
5 minutes
The catalog’s raw entry
[
  {
    "asset": "0x833589fCD6eDb6E08f4c7C32D4f71b54bdA02913",
    "extra": {
      "name": "USD Coin",
      "version": "2"
    },
    "payTo": "0xf8b2dD46542175AD46e14e6133340E652665F2Ee",
    "amount": "5000",
    "scheme": "exact",
    "network": "eip155:8453",
    "resource": "https://api.carbon-cashmere.de/v1/gas",
    "maxTimeoutSeconds": 300
  },
  {
    "asset": "0x3c499c542cEF5E3811e1192ce70d8cC03d5c3359",
    "extra": {
      "name": "USD Coin",
      "version": "2"
    },
    "payTo": "0xf8b2dD46542175AD46e14e6133340E652665F2Ee",
    "amount": "5000",
    "scheme": "exact",
    "network": "eip155:137",
    "resource": "https://api.carbon-cashmere.de/v1/gas",
    "maxTimeoutSeconds": 300
  },
  {
    "asset": "0xaf88d065e77c8cC2239327C5EDb3A432268e5831",
    "extra": {
      "name": "USD Coin",
      "version": "2"
    },
    "payTo": "0xf8b2dD46542175AD46e14e6133340E652665F2Ee",
    "amount": "5000",
    "scheme": "exact",
    "network": "eip155:42161",
    "resource": "https://api.carbon-cashmere.de/v1/gas",
    "maxTimeoutSeconds": 300
  },
  {
    "asset": "0x79A02482A880bCE3F13e09Da970dC34db4CD24d1",
    "extra": {
      "name": "USD Coin",
      "version": "2"
    },
    "payTo": "0xf8b2dD46542175AD46e14e6133340E652665F2Ee",
    "amount": "5000",
    "scheme": "exact",
    "network": "eip155:480",
    "resource": "https://api.carbon-cashmere.de/v1/gas",
    "maxTimeoutSeconds": 300
  },
  {
    "asset": "EPjFWdd5AufqSSqeM2qN1xzybapC8G4wEGGkZwyTDt1v",
    "extra": {
      "feePayer": "GVJJ7rdGiXr5xaYbRwRbjfaJL7fmwRygFi1H6aGqDveb"
    },
    "payTo": "GgS891nMiEETjBEFw1QQxVcAqsRV34mDYpxh24TrpCiD",
    "amount": "5000",
    "scheme": "exact",
    "network": "solana:5eykt4UsFv8P8NJdTREpY1vzqKqZKvdp",
    "resource": "https://api.carbon-cashmere.de/v1/gas",
    "maxTimeoutSeconds": 300
  },
  {
    "asset": "31566704",
    "extra": {
      "decimals": 6,
      "feePayer": "ZMFK2OI7ZBD2U27ISERZC4S6LKM6WMFJPZQ4MYNJDZ2VNBNMBA67RA22AA",
      "genesisId": "mainnet-v1.0",
      "genesisHash": "wGHE2Pwdvd7S12BL5FaOP20EGYesN73ktiC1qzkkit8="
    },
    "payTo": "5GRGZVUNRF2S4BY2TNRBCUCKUOT3H6BP56ACPCZVGR3ISTTRRSSB2RGJGI",
    "amount": "5000",
    "scheme": "exact",
    "network": "algorand:wGHE2Pwdvd7S12BL5FaOP20EGYesN73ktiC1qzkkit8=",
    "resource": "https://api.carbon-cashmere.de/v1/gas",
    "maxTimeoutSeconds": 300
  },
  {
    "asset": "USDC:GA5ZSEJYB37JRC5AVCIA5MOP4RHTM335X2KGX3IHOJAPP5RE34K4KZVN",
    "extra": {
      "decimals": 7,
      "areFeesSponsored": true
    },
    "payTo": "GDYFWCUFLG7MZAITOOVITYDNCLVJXWJ7OASYJAJPPOTONUQRNBCRO2VP",
    "amount": "50000",
    "scheme": "exact",
    "network": "stellar:pubnet",
    "resource": "https://api.carbon-cashmere.de/v1/gas",
    "maxTimeoutSeconds": 300
  }
]

Extensions

{
  "bazaar": {
    "info": {
      "input": {
        "type": "http",
        "method": "GET"
      },
      "output": {
        "type": "json",
        "example": {
          "eth_gas": {
            "fast_gwei": "0.08",
            "slow_gwei": "0.03",
            "standard_gwei": "0.05"
          },
          "btc_fees": {
            "fee_estimates": {
              "1": 12,
              "6": 5
            }
          }
        }
      }
    },
    "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",
                "HEAD",
                "DELETE"
              ],
              "type": "string"
            },
            "queryParams": {
              "type": "object",
              "properties": {}
            }
          },
          "additionalProperties": false
        },
        "output": {
          "type": "object",
          "required": [
            "type"
          ],
          "properties": {
            "type": {
              "type": "string"
            },
            "example": {
              "type": "object",
              "properties": {
                "eth_gas": {
                  "type": "object"
                },
                "btc_fees": {
                  "type": "object"
                }
              }
            }
          }
        }
      }
    }
  },
  "offer-receipt": {
    "info": {
      "offers": [
        {
          "format": "eip712",
          "payload": {
            "asset": "0x833589fCD6eDb6E08f4c7C32D4f71b54bdA02913",
            "payTo": "0xf8b2dD46542175AD46e14e6133340E652665F2Ee",
            "amount": "5000",
            "scheme": "exact",
            "network": "eip155:8453",
            "version": 1,
            "validUntil": 1779420042,
            "resourceUrl": "https://api.carbon-cashmere.de/v1/gas"
          },
          "signature": "0x6d62d4dd0ca2969afd0b572a954a3efb8afd9d50b37ae2135463fb2692caddff74553688c35dc67edbf96add8a80bb013ba1f5884bcf58bb22e05048d25f2ae51b",
          "acceptIndex": 0
        },
        {
          "format": "eip712",
          "payload": {
            "asset": "0x3c499c542cEF5E3811e1192ce70d8cC03d5c3359",
            "payTo": "0xf8b2dD46542175AD46e14e6133340E652665F2Ee",
            "amount": "5000",
            "scheme": "exact",
            "network": "eip155:137",
            "version": 1,
            "validUntil": 1779420042,
            "resourceUrl": "https://api.carbon-cashmere.de/v1/gas"
          },
          "signature": "0x9773771e20db37a2fdca2ece7fba66c0907043eddd9080a1d7e5f8fee86b893102bfcf1f9390899831b48bb013210f6aa6e57d4f618572280fe10337c35322051b",
          "acceptIndex": 1
        },
        {
          "format": "eip712",
          "payload": {
            "asset": "0xaf88d065e77c8cC2239327C5EDb3A432268e5831",
            "payTo": "0xf8b2dD46542175AD46e14e6133340E652665F2Ee",
            "amount": "5000",
            "scheme": "exact",
            "network": "eip155:42161",
            "version": 1,
            "validUntil": 1779420042,
            "resourceUrl": "https://api.carbon-cashmere.de/v1/gas"
          },
          "signature": "0x39a87941b7788f3eba74b00aeaa98cc96df67b4f7f35babb8981ad5d41d79a2220770bae634b19cc5924beb400abb1d2fe5c165e74b0eb8750fda5a527a5546a1c",
          "acceptIndex": 2
        },
        {
          "format": "eip712",
          "payload": {
            "asset": "0x79A02482A880bCE3F13e09Da970dC34db4CD24d1",
            "payTo": "0xf8b2dD46542175AD46e14e6133340E652665F2Ee",
            "amount": "5000",
            "scheme": "exact",
            "network": "eip155:480",
            "version": 1,
            "validUntil": 1779420042,
            "resourceUrl": "https://api.carbon-cashmere.de/v1/gas"
          },
          "signature": "0x2f73ad81ae27156aa6efff9e5a6848f354cdfe2e90fc92dbba18ae0581f46c15398acd89c04a411b439c8ce83ffa9d7c349b75da5f2a805998d3e3e22580df361b",
          "acceptIndex": 3
        },
        {
          "format": "eip712",
          "payload": {
            "asset": "EPjFWdd5AufqSSqeM2qN1xzybapC8G4wEGGkZwyTDt1v",
            "payTo": "GgS891nMiEETjBEFw1QQxVcAqsRV34mDYpxh24TrpCiD",
            "amount": "5000",
            "scheme": "exact",
            "network": "solana:5eykt4UsFv8P8NJdTREpY1vzqKqZKvdp",
            "version": 1,
            "validUntil": 1779420042,
            "resourceUrl": "https://api.carbon-cashmere.de/v1/gas"
          },
          "signature": "0x1b26dfeca4673a767b72bb37f3e6cd5f9b6b6feeefc55b964b87e561a49d40060b25de65e570d482ec6e0a4c88d429debd03217d9b49134d62275cdc917cf9fb1b",
          "acceptIndex": 4
        },
        {
          "format": "eip712",
          "payload": {
            "asset": "31566704",
            "payTo": "5GRGZVUNRF2S4BY2TNRBCUCKUOT3H6BP56ACPCZVGR3ISTTRRSSB2RGJGI",
            "amount": "5000",
            "scheme": "exact",
            "network": "algorand:wGHE2Pwdvd7S12BL5FaOP20EGYesN73ktiC1qzkkit8=",
            "version": 1,
            "validUntil": 1779420042,
            "resourceUrl": "https://api.carbon-cashmere.de/v1/gas"
          },
          "signature": "0x60b80ecf526fcb25a8c6466f6d5df26f762b477eb7ee8f6071a70d00e0f8af1740fe97828d2930aca407cbd667dac60d0720a4eedf4dba7cec30795ae9d8f6ab1b",
          "acceptIndex": 5
        },
        {
          "format": "eip712",
          "payload": {
            "asset": "USDC:GA5ZSEJYB37JRC5AVCIA5MOP4RHTM335X2KGX3IHOJAPP5RE34K4KZVN",
            "payTo": "GDYFWCUFLG7MZAITOOVITYDNCLVJXWJ7OASYJAJPPOTONUQRNBCRO2VP",
            "amount": "50000",
            "scheme": "exact",
            "network": "stellar:pubnet",
            "version": 1,
            "validUntil": 1779420042,
            "resourceUrl": "https://api.carbon-cashmere.de/v1/gas"
          },
          "signature": "0xebe40d824ecc86a574a15686bf6c59351174c8d6bfc950b3858c2686b6a532504588579bd35a7760fba45a0866590adf9d676817fc60abd70e1f89711951d3b81b",
          "acceptIndex": 6
        }
      ]
    },
    "schema": {
      "type": "object",
      "$schema": "https://json-schema.org/draft/2020-12/schema",
      "required": [
        "format",
        "payload",
        "signature"
      ],
      "properties": {
        "format": {
          "enum": [
            "eip712",
            "jws"
          ],
          "type": "string"
        },
        "payload": {
          "type": "object"
        },
        "signature": {
          "type": "string"
        }
      }
    }
  },
  "payment-identifier": {
    "info": {
      "required": false
    },
    "schema": {
      "type": "object",
      "$schema": "https://json-schema.org/draft/2020-12/schema",
      "required": [
        "required"
      ],
      "properties": {
        "id": {
          "type": "string",
          "pattern": "^[a-zA-Z0-9_-]+$",
          "maxLength": 128,
          "minLength": 16
        },
        "required": {
          "type": "boolean"
        }
      }
    }
  },
  "eip2612GasSponsoring": {
    "info": {
      "version": "1",
      "description": "The facilitator accepts EIP-2612 gasless Permit to Permit2 canonical contract."
    },
    "schema": {
      "type": "object",
      "$schema": "https://json-schema.org/draft/2020-12/schema",
      "required": [
        "from",
        "asset",
        "spender",
        "amount",
        "nonce",
        "deadline",
        "signature",
        "version"
      ],
      "properties": {
        "from": {
          "type": "string",
          "pattern": "^0x[a-fA-F0-9]{40}$",
          "description": "The address of the sender."
        },
        "asset": {
          "type": "string",
          "pattern": "^0x[a-fA-F0-9]{40}$",
          "description": "The address of the ERC-20 token contract."
        },
        "nonce": {
          "type": "string",
          "pattern": "^[0-9]+$",
          "description": "The current EIP-2612 nonce of the sender."
        },
        "amount": {
          "type": "string",
          "pattern": "^[0-9]+$",
          "description": "The amount to approve (uint256)."
        },
        "spender": {
          "type": "string",
          "pattern": "^0x[a-fA-F0-9]{40}$",
          "description": "The address of the spender (Canonical Permit2)."
        },
        "version": {
          "type": "string",
          "pattern": "^[0-9]+(\\.[0-9]+)*$",
          "description": "Schema version identifier."
        },
        "deadline": {
          "type": "string",
          "pattern": "^[0-9]+$",
          "description": "The timestamp at which the signature expires."
        },
        "signature": {
          "type": "string",
          "pattern": "^0x[a-fA-F0-9]+$",
          "description": "The 65-byte concatenated signature (r, s, v) as a hex string."
        }
      }
    }
  },
  "erc20ApprovalGasSponsoring": {
    "info": {
      "version": "1",
      "description": "The facilitator accepts a raw signed approval transaction and will sponsor the gas fees."
    },
    "schema": {
      "type": "object",
      "$schema": "https://json-schema.org/draft/2020-12/schema",
      "required": [
        "from",
        "asset",
        "spender",
        "amount",
        "signedTransaction",
        "version"
      ],
      "properties": {
        "from": {
          "type": "string",
          "pattern": "^0x[a-fA-F0-9]{40}$",
          "description": "The address of the sender."
        },
        "asset": {
          "type": "string",
          "pattern": "^0x[a-fA-F0-9]{40}$",
          "description": "The ERC-20 token contract address to approve."
        },
        "amount": {
          "type": "string",
          "pattern": "^[0-9]+$",
          "description": "Approval amount (uint256)."
        },
        "spender": {
          "type": "string",
          "pattern": "^0x[a-fA-F0-9]{40}$",
          "description": "The address of the spender (Canonical Permit2)."
        },
        "version": {
          "type": "string",
          "pattern": "^[0-9]+(\\.[0-9]+)*$",
          "description": "Schema version identifier."
        },
        "signedTransaction": {
          "type": "string",
          "pattern": "^0x[a-fA-F0-9]+$",
          "description": "RLP-encoded signed transaction calling ERC20.approve()."
        }
      }
    }
  }
}

Provenance

Seen in the source catalog
2026-05-22 02:20Z
Last indexed by Roundhouse
2026-06-11 02:50Z
Last enriched (probe, favicon, geo)
2026-09-10 23:15Z
x402 version
2
Max timeout
300s
Liveness probe
HTTP 401
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

No per-endpoint history for this service yet, so this is payments indexed to its PROVIDER's wallet over 30 days. 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 api.carbon-cashmere.de 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=api.carbon-cashmere.de'
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://api.carbon-cashmere.de/v1/gas, 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.