payment-ready until 2026-09-03
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.
VERDICT
ranking generation 3strong 96/100 #36 of 253 in Data by measured score
What the score read on this service: status online, 100% uptime 30d, 411ms response p95, x402 compliance 14 of 14, $0.005 price against the category. Each of those is measured, and each is published in full below.
The score comes from our own monitoring, never from reviews, operator claims, or a language model: reliability, x402 compliance, price against the category, a deterministic risk flag, and a small on-chain traction term, weighted by ranking generation 3. It is not placement anyone can buy: the paid verify tier is reported beside it and is not one of its inputs. Every component below stays published and read-only.
It is a score inside Data, and only there: price and speed are scored against the whole category field, every listing in it that carries no danger flag, the scored service included, which here means 253 listings, this one among them. That set is wider than the 253 the position above is counted against, because a listing we have measured too little of to rank still sits in the field the price and the speed are normalized over. The same service in a different field would read differently. The same engine answers GET /api/v1/best, and asked for a different pool (the whole directory, or another filter) it returns a different number for this service under this same ranking generation. Neither is more correct: they answer different questions, and the methodology states which is which.
Bands on the 0 to 100 measured score: strong at 93 and above, solid from 75, mixed from 55, weak below 55. Price and speed are scored against the whole category field, every listing in it that carries no danger flag, the scored service included, so the score places a service in its own field.
ALTERNATIVES IN DATA
Other Data services in this directory, ordered by the same measured score. The figures are ours: 30-day uptime from our own probes, 30-day settlement volume read on-chain (a conservative undercount, and null where we cannot measure it, never a zero).
| SERVICE | BAND | SCORE | UPTIME 30D | VOL 30D |
|---|---|---|---|---|
| WebberSites x402 Data API | strong | 99 | 100% | --- |
| API Acre | strong | 99 | 99.9% | --- |
| ForgeMesh Utility APIs | strong | 99 | 100% | --- |
| AgentFund US Economic, SEC & On-Chain Data | strong | 99 | 100% | --- |
| Agent Exchange | strong | 98 | 100% | --- |
ASSESSMENT
updated 6h agoThe parts the verdict above is computed from, each with its proof. Click any chip. Measured values stay read-only; unknown is honest, and an unknown is never counted as a zero.
reliability 100%
- uptime 24h
- 100%
- uptime 7d
- 100%
- uptime 30d
- 100%
- uptime 90d
- 100%
- response p95
- 411ms
- avg response
- 164ms
- total checks
- 2,768
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.
price $0.005 to $0.05 (p37 in Data)
- price (min)
- $0.005
- price (max)
- $0.05
- category percentile (min)
- p37 in Data
- category percentile (max)
- p61 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
- 6894d
- registrar
- MarkMonitor Inc.
- hosting
- custom
- domain created
- 2007-10-09
Identity facts, not a risk score.
traction ---
This service settles on a network x402-list does not measure yet, so on-chain volume is not counted here. Shown as unmeasured, not zero.
WHAT IT DOES
ai-derivedProvides attestation and verification services for data delivery and resolution
- category
- data-verification
- in
- query params
- auth
- api key
AI-generated summary. The measured data is never altered by it.
ENDPOINTS
| 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 | $0.005 | Base | USDC | header |
REQUEST / RESPONSE EXAMPLE
An unpaid request to GET /attest-delivery returns HTTP 402 with the payment terms. Settle onchain via your facilitator, then retry with the X-Payment header.
curl -i 'https://groundcheck.seiche.info/attest-delivery'
// 402 response (captured by monitor) · 4 payloads · click to expand
[
{
"error": "payment required (call with POST)",
"accepts": [
{
"asset": "0x833589fCD6eDb6E08f4c7C32D4f71b54bdA02913",
"extra": {
"name": "USD Coin",
"version": "2"
},
"payTo": "0x5B4A78b7EFe482d1579E287dA6F0043f89cf0EA1",
"amount": "20000",
"scheme": "exact",
"network": "eip155:8453",
"maxTimeoutSeconds": 60
}
],
"resource": {
"url": "https://groundcheck.seiche.info/check",
"tags": [
"grounding",
"citations",
"verified-data",
"delivery-receipts",
"agentic-commerce"
],
"iconUrl": "https://groundcheck.seiche.info/favicon.ico",
"mimeType": "application/json",
"description": "Claim grounding and citation attestation for AI agents: verified enrichment that adds a veracity field to text. Each factual claim is grounded against live web sources (Wikipedia + world news) and returned with a machine-verified verdict (supported/refuted/unverified), a confidence score, and cited sources. Refuses to guess on conflicting evidence. Built for research agents that must cite, citation-locked content, and compliance checks.",
"serviceName": "Groundcheck"
},
"extensions": {
"bazaar": {
"info": {
"input": {
"body": {
"text": "The Eiffel Tower was completed in 1889. It is 330 metres tall.",
"max_claims": 8
},
"type": "http",
"method": "POST",
"bodyType": "json"
},
"output": {
"type": "json",
"example": {
"report": [
{
"claim": "The Eiffel Tower was completed in 1889.",
"verdict": "supported",
"rationale": "sources support and none refute",
"confidence": 0.83
}
],
"backend": "wikipedia+gdelt",
"checked": 2,
"classifier": "free-llm-router"
}
}
},
"schema": {
"type": "object",
"$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.
Median across 4 endpoints. Use the selector to isolate one.
checklist grew 11->14 on 2026-07-28; a step here is a metric change, not a regression
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.
COMPLIANCE
14/14 checks pass · grade Alast 402 captured 2026-07-21 · last up 2026-08-27
- 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
EMBED THIS BADGE
<a href="https://x402-list.com/services/groundcheck?utm_source=badge&utm_medium=referral&utm_campaign=embed"> <img src="https://x402-list.com/badge/groundcheck.svg" alt="Groundcheck listed on x402-list" height="28"> </a>
[](https://x402-list.com/services/groundcheck?utm_source=badge&utm_medium=referral&utm_campaign=embed)
<a href="https://x402-list.com/services/groundcheck?utm_source=badge&utm_medium=referral&utm_campaign=embed"> <img src="https://x402-list.com/badge/groundcheck.svg?data=uptime" alt="Groundcheck uptime on x402-list" height="28"> </a>