x402 List

x402 Protocol Service Directory

●

Groundcheck

Data PAYMENT-READY

payment-ready until 2026-08-20

Groundcheck is verified enrichment for AI agents. Send a factual claim and it returns a machine verified verdict with a confidence score and cited sources, grounded against live web sources. Identity protocols verify who an agent is; Groundcheck verifies what it says. Single claim grounding is free. Paid endpoints over x402: claim extraction and instrument resolution at 0.005 USDC, document grounding at 0.02, and delivery attestation at 0.05, which returns a signed receipt binding the x402 payment to the delivered content, verifiable offline. v1 and v2 both accepted. No account and no API key.

Pay from $0.005 to $0.05 per request in USDC on Base, settled onchain via the x402 protocol, no signup, no API key needed.

first settlement 2026-07-13 · $0.25 all-time · settled via coinbase

BASE URL https://groundcheck.seiche.info │ WEBSITE https://github.com/beepboop2025/groundcheck │ ENDPOINTS 4 │ NETWORK Base │ ASSET USDC │ MEMBER SINCE 2026-07-12 │ MONITORED SINCE 2026-07-12

ASSESSMENT

updated 4h ago

Evidence-backed signals, not a single score. Click any chip for the proof. Measured values stay read-only; unknown is honest.

reliability 100%
uptime 24h
100%
uptime 7d
100%
uptime 30d
100%
uptime 90d
100%
response p95
686ms
avg response
148ms
total checks
2,736

Measured on the unpaid 402 handshake, not the paid call. A service can 402 correctly and still fail after payment.

compliance A (14/14)

14 of 14 x402 conformance checks pass. Full checklist below.

jump to compliance checklist

price $0.005 to $0.05 (p35 in Data)
price (min)
$0.005
price (max)
$0.05
category percentile (min)
p35 in Data
category percentile (max)
p62 in Data
endpoints / prices
4 / 3
model
tiered
stability
100%
risk clean

No deterministic risk flag. Risk fires only on an exact blocklist match, or a reserved-brand name with a mismatched verified payTo. Never from low uptime, a high price, or a model guess.

domain age
6880d
registrar
MarkMonitor Inc.
hosting
custom
domain created
2007-10-09

Identity facts, not a risk score.

traction $0.215 30d · 1 buyers · top buyer 100%
volume 30d
$0.215
buyers 30d
1
settlements 30d
10
first settlement
2026-07-13
last settlement
2026-07-20
top buyer share
100% of 30d volume
trend 7d vs 30d
0.00x the 30d daily rate
networks
eip155:8453
volume all-time
$0.25
settlements all-time
12
median settlement 30d
$0.0125
max settlement 30d
$0.05
settled via
coinbase ($0.21, 10 tx)

Conservative undercount: only USDC settlements via facilitators we measure are counted. A measured floor, not an estimate.

Top buyer share is a concentration signal, not part of the ranking score.

WHAT IT DOES

ai-derived

Provides attestation and verification services for data delivery and resolution

category
data-verification
in
query params
auth
api key
attestationverificationdata-deliveryresolution

AI-generated summary. The measured data is never altered by it.

ENDPOINTS

Service endpoints with HTTP method, path, description, pricing, and network
METHOD PATH DESCRIPTION PRICE NETWORK ASSET 402 CHANNEL
GET /attest-delivery $0.05 Base USDC header
GET /check $0.02 Base USDC header
GET /extract $0.005 Base USDC header
GET /resolve $0.005 Base USDC header
4 endpoints

REQUEST / RESPONSE EXAMPLE

An unpaid request to GET /attest-delivery returns HTTP 402 with the payment terms. Settle onchain via your facilitator, then retry with the X-Payment header.

// request
curl -i 'https://groundcheck.seiche.info/attest-delivery'
// 402 response (captured by monitor) · 4 payloads · click to expand 
[
  {
    "error": "payment required (call with POST)",
    "accepts": [
      {
        "asset": "0x833589fCD6eDb6E08f4c7C32D4f71b54bdA02913",
        "extra": {
          "name": "USD Coin",
          "version": "2"
        },
        "payTo": "0x5B4A78b7EFe482d1579E287dA6F0043f89cf0EA1",
        "amount": "20000",
        "scheme": "exact",
        "network": "eip155:8453",
        "maxTimeoutSeconds": 60
      }
    ],
    "resource": {
      "url": "https://groundcheck.seiche.info/check",
      "tags": [
        "grounding",
        "citations",
        "verified-data",
        "delivery-receipts",
        "agentic-commerce"
      ],
      "iconUrl": "https://groundcheck.seiche.info/favicon.ico",
      "mimeType": "application/json",
      "description": "Claim grounding and citation attestation for AI agents: verified enrichment that adds a veracity field to text. Each factual claim is grounded against live web sources (Wikipedia + world news) and returned with a machine-verified verdict (supported/refuted/unverified), a confidence score, and cited sources. Refuses to guess on conflicting evidence. Built for research agents that must cite, citation-locked content, and compliance checks.",
      "serviceName": "Groundcheck"
    },
    "extensions": {
      "bazaar": {
        "info": {
          "input": {
            "body": {
              "text": "The Eiffel Tower was completed in 1889. It is 330 metres tall.",
              "max_claims": 8
            },
            "type": "http",
            "method": "POST",
            "bodyType": "json"
          },
          "output": {
            "type": "json",
            "example": {
              "report": [
                {
                  "claim": "The Eiffel Tower was completed in 1889.",
                  "verdict": "supported",
                  "rationale": "sources support and none refute",
                  "confidence": 0.83
                }
              ],
              "backend": "wikipedia+gdelt",
              "checked": 2,
              "classifier": "free-llm-router"
            }
          }
        },
        "schema": {
          "type": "object",
          "$schema": "https://json-schema.org/draft/2020-12/schema",
          "required": [
            "input"
          ],
          "properties": {
            "input": {
              "type": "object",
              "required": [
                "type",
                "method",
                "body"
              ],
              "properties": {
                "body": {
                  "type": "object",
                  "required": [
                    "text"
                  ],
                  "properties": {
                    "text": {
                      "type": "string",
                      "minLength": 1,
                      "description": "Document whose factual claims to verify"
                    },
                    "max_claims": {
                      "type": "integer",
                      "maximum": 20,
                      "minimum": 1
                    }
                  }
                },
                "type": {
                  "type": "string",
                  "const": "http"
                },
                "method": {
                  "type": "string",
                  "const": "POST"
                },
                "bodyType": {
                  "type": "string",
                  "const": "json"
                }
              },
              "additionalProperties": false
            },
            "output": {
              "type": "object",
              "required": [
                "type"
              ],
              "properties": {
                "type": {
                  "type": "string",
                  "const": "json"
                },
                "example": {
                  "type": "object"
                }
              }
            }
          }
        },
        "routeTemplate": "/check"
      }
    },
    "x402Version": 2
  },
  {
    "error": "payment required (call with POST)",
    "accepts": [
      {
        "asset": "0x833589fCD6eDb6E08f4c7C32D4f71b54bdA02913",
        "extra": {
          "name": "USD Coin",
          "version": "2"
        },
        "payTo": "0x5B4A78b7EFe482d1579E287dA6F0043f89cf0EA1",
        "amount": "5000",
        "scheme": "exact",
        "network": "eip155:8453",
        "maxTimeoutSeconds": 60
      }
    ],
    "resource": {
      "url": "https://groundcheck.seiche.info/resolve",
      "tags": [
        "grounding",
        "citations",
        "verified-data",
        "delivery-receipts",
        "agentic-commerce"
      ],
      "iconUrl": "https://groundcheck.seiche.info/favicon.ico",
      "mimeType": "application/json",
      "description": "Attested instrument-identity enrichment for AI agents: map a ticker, ISIN, CUSIP, SEDOL, FIGI, or instrument name to canonical FIGI records (name, security type, market sector, exchange) via Bloomberg open symbology, with provenance (source, retrieval time) attached to every answer. Built for agents that must know WHICH security a claim, order, or document is about before acting on it.",
      "serviceName": "Groundcheck"
    },
    "extensions": {
      "bazaar": {
        "info": {
          "input": {
            "body": {
              "query": "AAPL",
              "max_results": 3
            },
            "type": "http",
            "method": "POST",
            "bodyType": "json"
          },
          "output": {
            "type": "json",
            "example": {
              "query": "AAPL",
              "id_type": "TICKER",
              "matched": true,
              "provenance": {
                "url": "https://api.openfigi.com/v3",
                "source": "OpenFIGI (Bloomberg open symbology)",
                "retrieved_at": "2026-07-13T00:00:00+00:00"
              },
              "instruments": [
                {
                  "figi": "BBG000B9XRY4",
                  "name": "APPLE INC",
                  "ticker": "AAPL",
                  "exch_code": "US",
                  "market_sector": "Equity",
                  "security_type": "Common Stock"
                }
              ]
            }
          }
        },
        "schema": {
          "type": "object",
          "$schema": "https://json-schema.org/draft/2020-12/schema",
          "required": [
            "input"
          ],
          "properties": {
            "input": {
              "type": "object",
              "required": [
                "type",
                "method",
                "body"
              ],
              "properties": {
                "body": {
                  "type": "object",
                  "required": [
                    "query"
                  ],
                  "properties": {
                    "query": {
                      "type": "string",
                      "minLength": 1,
                      "description": "Ticker, ISIN, CUSIP, SEDOL, FIGI, or instrument name to resolve"
                    },
                    "id_type": {
                      "enum": [
                        "TICKER",
                        "ID_ISIN",
                        "ID_CUSIP",
                        "ID_SEDOL",
                        "ID_BB_GLOBAL"
                      ],
                      "type": "string",
                      "description": "Optional; auto-detected from the value's shape when omitted"
                    },
                    "max_results": {
                      "type": "integer",
                      "maximum": 10,
                      "minimum": 1
                    }
                  }
                },
                "type": {
                  "type": "string",
                  "const": "http"
                },
                "method": {
                  "type": "string",
                  "const": "POST"
                },
                "bodyType": {
                  "type": "string",
                  "const": "json"
                }
              },
              "additionalProperties": false
            },
            "output": {
              "type": "object",
              "required": [
                "type"
              ],
              "properties": {
                "type": {
                  "type": "string",
                  "const": "json"
                },
                "example": {
                  "type": "object"
                }
              }
            }
          }
        },
        "routeTemplate": "/resolve"
      }
    },
    "x402Version": 2
  },
  {
    "error": "payment required (call with POST)",
    "accepts": [
      {
        "asset": "0x833589fCD6eDb6E08f4c7C32D4f71b54bdA02913",
        "extra": {
          "name": "USD Coin",
          "version": "2"
        },
        "payTo": "0x5B4A78b7EFe482d1579E287dA6F0043f89cf0EA1",
        "amount": "5000",
        "scheme": "exact",
        "network": "eip155:8453",
        "maxTimeoutSeconds": 60
      }
    ],
    "resource": {
      "url": "https://groundcheck.seiche.info/extract",
      "tags": [
        "grounding",
        "citations",
        "verified-data",
        "delivery-receipts",
        "agentic-commerce"
      ],
      "iconUrl": "https://groundcheck.seiche.info/favicon.ico",
      "mimeType": "application/json",
      "description": "Claim extraction for agent verification loops: split text into independently checkable atomic factual claims via auditable rule-based decomposition (no LLM guessing), with a signed receipt bound to the input hash. The cheap first step of the loop — extract here, then ground what matters via /verify or /check.",
      "serviceName": "Groundcheck"
    },
    "extensions": {
      "bazaar": {
        "info": {
          "input": {
            "body": {
              "text": "The Eiffel Tower was completed in 1889 and is 330 metres tall.",
              "max_claims": 20
            },
            "type": "http",
            "method": "POST",
            "bodyType": "json"
          },
          "output": {
            "type": "json",
            "example": {
              "count": 2,
              "claims": [
                "The Eiffel Tower was completed in 1889",
                "is 330 metres tall."
              ],
              "method": "sentence-heuristic + rule-based atom decomposition",
              "attestation": {
                "receipt": {
                  "…": "…"
                },
                "attested": true
              },
              "input_sha256": "…64 hex…"
            }
          }
        },
        "schema": {
          "type": "object",
          "$schema": "https://json-schema.org/draft/2020-12/schema",
          "required": [
            "input"
          ],
          "properties": {
            "input": {
              "type": "object",
              "required": [
                "type",
                "method",
                "body"
              ],
              "properties": {
                "body": {
                  "type": "object",
                  "required": [
                    "text"
                  ],
                  "properties": {
                    "text": {
                      "type": "string",
                      "minLength": 1,
                      "description": "Text to split into independently checkable atomic factual claims"
                    },
                    "max_claims": {
                      "type": "integer",
                      "maximum": 50,
                      "minimum": 1
                    }
                  }
                },
                "type": {
                  "type": "string",
                  "const": "http"
                },
                "method": {
                  "type": "string",
                  "const": "POST"
                },
                "bodyType": {
                  "type": "string",
                  "const": "json"
                }
              },
              "additionalProperties": false
            },
            "output": {
              "type": "object",
              "required": [
                "type"
              ],
              "properties": {
                "type": {
                  "type": "string",
                  "const": "json"
                },
                "example": {
                  "type": "object"
                }
              }
            }
          }
        },
        "routeTemplate": "/extract"
      }
    },
    "x402Version": 2
  },
  {
    "error": "payment required (call with POST)",
    "accepts": [
      {
        "asset": "0x833589fCD6eDb6E08f4c7C32D4f71b54bdA02913",
        "extra": {
          "name": "USD Coin",
          "version": "2"
        },
        "payTo": "0x5B4A78b7EFe482d1579E287dA6F0043f89cf0EA1",
        "amount": "50000",
        "scheme": "exact",
        "network": "eip155:8453",
        "maxTimeoutSeconds": 60
      }
    ],
    "resource": {
      "url": "https://groundcheck.seiche.info/attest-delivery",
      "tags": [
        "grounding",
        "citations",
        "verified-data",
        "delivery-receipts",
        "agentic-commerce"
      ],
      "iconUrl": "https://groundcheck.seiche.info/favicon.ico",
      "mimeType": "application/json",
      "description": "Signed delivery receipts for agentic commerce: submit what a paid service returned (plus its x402 settlement receipt and advertised schema) and receive an offline-verifiable Ed25519 attestation binding payment to delivery to grounded content — schema conformance, machine-verified claim verdicts, and a neutral accountability trail for disputes between agents and the services they pay.",
      "serviceName": "Groundcheck"
    },
    "extensions": {
      "bazaar": {
        "info": {
          "input": {
            "body": {
              "service": "https://api.example-data-service.xyz/enrich",
              "response_text": "{\"figi\": \"BBG000B9XRY4\", \"name\": \"APPLE INC\"}",
              "payment_receipt": "<X-PAYMENT-RESPONSE value>",
              "advertised_schema": {
                "type": "object",
                "required": [
                  "figi",
                  "name"
                ]
              }
            },
            "type": "http",
            "method": "POST",
            "bodyType": "json"
          },
          "output": {
            "type": "json",
            "example": {
              "payment": {
                "bound": true,
                "network": "base",
                "success": true,
                "transaction": "0x…"
              },
              "service": "https://api.example-data-service.xyz/enrich",
              "grounding": {
                "checked": 1,
                "refuted": 0,
                "supported": 1,
                "unverified": 0
              },
              "rationale": "no refuted claims; 1 claim(s) supported by evidence and the advertised schema validates",
              "attestation": {
                "receipt": {
                  "…": "…"
                },
                "attested": true
              },
              "conformance": {
                "valid": true,
                "checked": true,
                "problems": []
              },
              "response_sha256": "…64 hex…",
              "delivery_verdict": "consistent"
            }
          }
        },
        "schema": {
          "type": "object",
          "$schema": "https://json-schema.org/draft/2020-12/schema",
          "required": [
            "input"
          ],
          "properties": {
            "input": {
              "type": "object",
              "required": [
                "type",
                "method",
                "body"
              ],
              "properties": {
                "body": {
                  "type": "object",
                  "required": [
                    "service",
                    "response_text"
                  ],
                  "properties": {
                    "service": {
                      "type": "string",
                      "minLength": 1,
                      "description": "URL (or name) of the paid service whose delivery is being verified"
                    },
                    "max_claims": {
                      "type": "integer",
                      "maximum": 20,
                      "minimum": 1
                    },
                    "request_text": {
                      "type": "string",
                      "description": "What was asked of the service (optional; bound by hash when given)"
                    },
                    "response_text": {
                      "type": "string",
                      "minLength": 1,
                      "description": "The delivered payload, verbatim (JSON or prose)"
                    },
                    "payment_receipt": {
                      "type": "string",
                      "description": "x402 settlement receipt from the paid call (X-PAYMENT-RESPONSE value, base64 or JSON)"
                    },
                    "advertised_schema": {
                      "type": "object",
                      "description": "JSON schema the service advertised for its output"
                    }
                  }
                },
                "type": {
                  "type": "string",
                  "const": "http"
                },
                "method": {
                  "type": "string",
                  "const": "POST"
                },
                "bodyType": {
                  "type": "string",
                  "const": "json"
                }
              },
              "additionalProperties": false
            },
            "output": {
              "type": "object",
              "required": [
                "type"
              ],
              "properties": {
                "type": {
                  "type": "string",
                  "const": "json"
                },
                "example": {
                  "type": "object"
                }
              }
            }
          }
        },
        "routeTemplate": "/attest-delivery"
      }
    },
    "x402Version": 2
  }
]

OVER TIME

All charts use the 30d selector; each series spans only the dates it has data for. Every series is also served as JSON at /api/v1/services/groundcheck/price, /scores, /volume and /buyers. On-chain volume and distinct buyers are measured over the service's settlement address and are a conservative undercount (only settlements that reach a measured facilitator are counted). The on-chain series roll up hourly, so the latest day can be up to about an hour behind; distinct buyers are counted per payout address, so a service that settles to more than one address is an upper bound.

UPTIME
07-15 · uptime 100.0% · 197ms avg07-16 · uptime 100.0% · 294ms avg07-17 · uptime 100.0% · 135ms avg07-18 · uptime 100.0% · 170ms avg07-19 · uptime 100.0% · 137ms avg07-20 · uptime 100.0% · 139ms avg07-21 · uptime 100.0% · 165ms avg07-22 · uptime 100.0% · 82ms avg07-23 · uptime 100.0% · 71ms avg07-24 · uptime 100.0% · 64ms avg07-25 · uptime 100.0% · 55ms avg07-26 · uptime 100.0% · 67ms avg07-27 · uptime 100.0% · 87ms avg07-28 · uptime 100.0% · 102ms avg07-29 · uptime 100.0% · 107ms avg07-30 · uptime 100.0% · 114ms avg07-31 · uptime 100.0% · 106ms avg08-01 · uptime 100.0% · 171ms avg08-02 · uptime 100.0% · 142ms avg08-03 · uptime 100.0% · 129ms avg08-04 · uptime 100.0% · 159ms avg08-05 · uptime 100.0% · 274ms avg08-06 · uptime 100.0% · 255ms avg08-07 · uptime 100.0% · 177ms avg08-08 · uptime 100.0% · 202ms avg08-09 · uptime 100.0% · 85ms avg08-10 · uptime 100.0% · 160ms avg08-11 · uptime 100.0% · 150ms avg08-12 · uptime 100.0% · 133ms avg08-13 · uptime 100.0% · 393ms avg07-1508-13
30d UPTIME 100%
RESPONSE TIME
07-15 · 197ms avg07-15 · 197ms avg07-16 · 294ms avg07-16 · 294ms avg07-17 · 135ms avg07-17 · 135ms avg07-18 · 170ms avg07-18 · 170ms avg07-19 · 137ms avg07-19 · 137ms avg07-20 · 139ms avg07-20 · 139ms avg07-21 · 165ms avg07-21 · 165ms avg07-22 · 82ms avg07-22 · 82ms avg07-23 · 71ms avg07-23 · 71ms avg07-24 · 64ms avg07-24 · 64ms avg07-25 · 55ms avg07-25 · 55ms avg07-26 · 67ms avg07-26 · 67ms avg07-27 · 87ms avg07-27 · 87ms avg07-28 · 102ms avg07-28 · 102ms avg07-29 · 107ms avg07-29 · 107ms avg07-30 · 114ms avg07-30 · 114ms avg07-31 · 106ms avg07-31 · 106ms avg08-01 · 171ms avg08-01 · 171ms avg08-02 · 142ms avg08-02 · 142ms avg08-03 · 129ms avg08-03 · 129ms avg08-04 · 159ms avg08-04 · 159ms avg08-05 · 274ms avg08-05 · 274ms avg08-06 · 255ms avg08-06 · 255ms avg08-07 · 177ms avg08-07 · 177ms avg08-08 · 202ms avg08-08 · 202ms avg08-09 · 85ms avg08-09 · 85ms avg08-10 · 160ms avg08-10 · 160ms avg08-11 · 150ms avg08-11 · 150ms avg08-12 · 133ms avg08-12 · 133ms avg08-13 · 393ms avg08-13 · 393ms avg07-1508-13
AVG RESP 151ms
PRICE (captured 402, USD)
07-14 · $0.0207-21 · $0.012508-13 · $0.0125$0.012507-1408-13

Median across 4 endpoints. Use the selector to isolate one.

SUB-SCORES (uptime + x402 compliance)
07-15 uptime: 99.6% compliance: 92% checks07-16 uptime: 99.7% compliance: 92% checks07-17 uptime: 99.8% compliance: 100% checks07-18 uptime: 99.8% compliance: 100% checks07-19 uptime: 99.8% compliance: 100% checks07-20 uptime: 99.9% compliance: 100% checks07-21 uptime: 99.9% compliance: 100% checks07-22 uptime: 99.9% compliance: 100% checks07-23 uptime: 99.9% compliance: 100% checks07-24 uptime: 99.9% compliance: 100% checks07-25 uptime: 99.9% compliance: 100% checks07-26 uptime: 99.9% compliance: 100% checks07-27 uptime: 99.9% compliance: 100% checks07-28 uptime: 99.9% compliance: 100% checks07-29 uptime: 99.9% compliance: 100% checks07-30 uptime: 99.9% compliance: 100% checks07-31 uptime: 99.9% compliance: 100% checks08-01 uptime: 99.9% compliance: 100% checks08-02 uptime: 99.9% compliance: 100% checks08-03 uptime: 99.9% compliance: 100% checks08-04 uptime: 100.0% compliance: 100% checks08-05 uptime: 100.0% compliance: 100% checks08-06 uptime: 100.0% compliance: 100% checks08-07 uptime: 100.0% compliance: 100% checks08-08 uptime: 100.0% compliance: 100% checks08-09 uptime: 100.0% compliance: 100% checks08-10 uptime: 100.0% compliance: 100% checks08-11 uptime: 100.0% compliance: 100% checks08-12 uptime: 100.0% compliance: 100% checks08-13 uptime: 100.0% compliance: 100% checksuptimecompliance07-1508-13

checklist grew 11->14 on 2026-07-28; a step here is a metric change, not a regression

PILLARS OVER TIME (measured)
price percentile in Data
site signals present (of 6)

Measured site and economics pillars from the assessment history, so the latest value shown elsewhere on this page reads as a point on a trend rather than a permanent state.

VOLUME (on-chain settlement, USD)
building volume history (1 day so far)
DISTINCT BUYERS
building buyer history (1 day so far)

COMPLIANCE

14/14 checks pass · grade A

last 402 captured 2026-07-21 · last up 2026-08-13

  • 402 payload captured
  • accepts[] array present
  • payTo address recoverable
  • payTo at accepts[0].payTo (conformant shape)
  • payTo is a valid on-chain address
  • atomic price declared
  • atomic price in a sane range
  • asset (token) address declared
  • network resolves to CAIP-2
  • payment scheme declared
  • served over HTTPS
  • declares the current x402 version (2)
  • EIP-712 domain parameters present on every EVM entry
  • x402 v2 envelope delivered in the payment-required header

SITE PILLARS

  • homepage reachable
  • openapi doc
  • pricing page
  • llms.txt
  • robots.txt
  • terms page
recent checks (18) live · click to expand
TIME STATUS RESP CAUSE
● OK 145ms
● SLOW 440ms
● SLOW 632ms
● SLOW 1191ms
● SLOW 1169ms
● OK 183ms
● SLOW 905ms
● SLOW 772ms
● SLOW 754ms
● SLOW 788ms
● SLOW 716ms
● SLOW 961ms
● SLOW 443ms
● SLOW 1121ms
● SLOW 992ms
● SLOW 776ms
● SLOW 704ms
● SLOW 1045ms
18 of 2,749 checks · live count

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Show that Groundcheck is monitored on x402-list. Paste this on your site or README, it links back to this live listing.

Groundcheck listed on x402-list
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Groundcheck uptime on x402-list
live uptime
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// HTML · live uptime variant
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</a>

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