Penny Army Reference Metadata
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SearchLiveeip155:8453Exactvia cdp
ResearchCitationsDoiCrossrefMetadata
Calls · 30d
3
This endpoint's own trailing-30-day call count, as published by the upstream catalog and snapshotted daily. 6 snapshots so far.
$0.15
Verified settled volume
3 settlements proven x402 by their on-chain EIP-3009 marker.
$0.050
Listed price
As published in the catalog. Always read the live 402 before paying.
3
Calls · 30d
Upstream's own call count for this endpoint, not ours.
1
Unique payers · 30d
Last called 2026-09-22 18:56Z
—
Upstream on-chain volume
Reported by the source catalog.
Paid to
0xce53bde2C7a639fc5526AC006a8A7866625d1342The 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.
{
"accepts": [
{
"asset": "0x833589fCD6eDb6E08f4c7C32D4f71b54bdA02913",
"extra": {
"name": "USD Coin",
"version": "2",
"paymentFlow": "authorization",
"assetTransferMethod": "eip3009"
},
"payTo": "0xce53bde2C7a639fc5526AC006a8A7866625d1342",
"amount": "50000",
"scheme": "exact",
"network": "eip155:8453",
"maxTimeoutSeconds": 60
}
],
"resource": {
"url": "https://penny-army-reference-mainnet.spruceboundgranitestudio.workers.dev/v1/compare-reference-metadata",
"tags": [
"research",
"citations",
"doi",
"crossref",
"metadata"
],
"mimeType": "application/json",
"description": "Compare 1-10 DOI-bearing references against Crossref metadata: supplied title, ordered authors and/or year. Returns field agreements, discrepancies, ambiguities and provenance; does not verify scientific claims. 0.05 native USDC per completed batch on Base. Failed retrieval prevents settlement. Original-result recovery lasts 24 hours. Purchases require X-Penny-Mainnet-Key and an explicitly opened bounded window; sales are paused by default. Examples are saved fixtures.",
"serviceName": "Penny Army Reference Metadata"
},
"extensions": {
"bazaar": {
"info": {
"input": {
"body": {
"references": [
{
"id": "forest-mutation",
"doi": "10.1023/a:1010933404324",
"year": 2002
}
]
},
"type": "http",
"method": "POST",
"bodyType": "json"
},
"output": {
"type": "json",
"example": {
"records": [
{
"id": "forest-mutation",
"doi": "10.1023/a:1010933404324",
"fields": [
{
"field": "title",
"status": "not_supplied",
"supplied": null,
"retrieved": [
"Random Forests"
]
},
{
"field": "authors",
"status": "not_supplied",
"supplied": null,
"retrieved": [
{
"given": "Leo",
"family": "Breiman"
}
]
},
{
"field": "year",
"status": "disagree",
"supplied": 2002,
"retrieved": {
"issued": [
[
2001,
10
]
],
"published": [
[
2001,
10
]
],
"published-print": [
[
2001,
10
]
]
}
}
],
"provenance": {
"url": "https://api.crossref.org/works/10.1023%2Fa%3A1010933404324",
"source": "Crossref",
"retrieved_at": "2026-09-09T16:16:30.570Z"
},
"ambiguities": [],
"not_supplied": [
"title",
"authors"
],
"discrepancies": [
"year"
],
"missing_checks": [],
"identifier_outcome": "found",
"unavailable_checks": []
}
],
"test_only": false,
"schema_version": "1.0"
}
}
},
"schema": {
"type": "object",
"$schema": "https://json-schema.org/draft/2020-12/schema",
"required": [
"input"
],
"properties": {
"input": {
"type": "object",
"required": [
"type",
"method",
"bodyType",
"body"
],
"properties": {
"body": {
"type": "object",
"$schema": "https://json-schema.org/draft/2020-12/schema",
"required": [
"references"
],
"properties": {
"references": {
"type": "array",
"items": {
"type": "object",
"anyOf": [
{
"required": [
"title"
]
},
{
"required": [
"authors"
]
},
{
"required": [
"year"
]
}
],
"required": [
"id",
"doi"
],
"properties": {
"id": {
"type": "string",
"maxLength": 64,
"minLength": 1
},
"doi": {
"type": "string",
"pattern": "^10\\.\\d{4,9}\\/[^\\s\\x00-\\x20?#%\\\\]+$",
"maxLength": 200
},
"year": {
"type": "integer",
"maximum": 9999,
"minimum": 1
},
"title": {
"type": "string",
"maxLength": 2000,
"minLength": 1
},
"authors": {
"type": "array",
"items": {
"type": "object",
"required": [
"family"
],
"properties": {
"given": {
"type": "string",
"maxLength": 200,
"minLength": 1
},
"family": {
"type": "string",
"maxLength": 200,
"minLength": 1
}
},
"additionalProperties": false
},
"maxItems": 40,
"minItems": 1
}
},
"additionalProperties": false
},
"maxItems": 10,
"minItems": 1
}
},
"description": "One to ten DOI-bearing records, each with at least one title, authors or year. Record IDs must be unique within a batch (case-sensitive); JSON Schema does not enforce uniqueness by id. DOIs, titles and author names are trimmed before runtime validation; DOIs are lowercased. Whitespace-only titles/names are rejected. application/json is required; the raw UTF-8 body is limited to 32768 bytes and a five-second input deadline.",
"additionalProperties": false
},
"type": {
"type": "string",
"const": "http"
},
"method": {
"enum": [
"POST"
],
"type": "string"
},
"bodyType": {
"enum": [
"json",
"form-data",
"text"
],
"type": "string"
}
},
"additionalProperties": false
},
"output": {
"type": "object",
"required": [
"type"
],
"properties": {
"type": {
"type": "string"
},
"example": {
"type": "object",
"$schema": "https://json-schema.org/draft/2020-12/schema",
"required": [
"schema_version",
"test_only",
"records"
],
"properties": {
"records": {
"type": "array",
"items": {
"type": "object",
"required": [
"id",
"doi",
"identifier_outcome",
"provenance",
"fields",
"discrepancies",
"ambiguities",
"missing_checks",
"unavailable_checks",
"not_supplied"
],
"properties": {
"id": {
"type": "string"
},
"doi": {
"type": "string"
},
"fields": {
"type": "array",
"items": {
"type": "object",
"required": [
"field",
"supplied",
"retrieved",
"status"
],
"properties": {
"field": {
"enum": [
"title",
"authors",
"year"
],
"type": "string"
},
"status": {
"enum": [
"agree",
"disagree",
"ambiguous",
"missing",
"unavailable",
"not_supplied"
],
"type": "string"
},
"supplied": {
"anyOf": [
{
"type": "string"
},
{
"type": "number"
},
{
"type": "null"
},
{
"type": "array",
"items": {
"type": "string"
}
},
{
"type": "array",
"items": {
"type": "object",
"properties": {
"given": {
"type": "string",
"maxLength": 200
},
"family": {
"type": "string",
"maxLength": 200
}
},
"additionalProperties": false
}
},
{
"type": "object",
"propertyNames": {
"type": "string"
},
"additionalProperties": {
"type": "array",
"items": {
"type": "array",
"items": {
"type": "number"
}
}
}
}
]
},
"retrieved": {
"anyOf": [
{
"type": "string"
},
{
"type": "number"
},
{
"type": "null"
},
{
"type": "array",
"items": {
"type": "string"
}
},
{
"type": "array",
"items": {
"type": "object",
"properties": {
"given": {
"type": "string",
"maxLength": 200
},
"family": {
"type": "string",
"maxLength": 200
}
},
"additionalProperties": false
}
},
{
"type": "object",
"propertyNames": {
"type": "string"
},
"additionalProperties": {
"type": "array",
"items": {
"type": "array",
"items": {
"type": "number"
}
}
}
}
]
}
},
"additionalProperties": false
}
},
"provenance": {
"type": "object",
"required": [
"source",
"url",
"retrieved_at"
],
"properties": {
"url": {
"type": "string"
},
"source": {
"type": "string",
"const": "Crossref"
},
"retrieved_at": {
"type": [
"string",
"null"
]
}
},
"additionalProperties": false
},
"ambiguities": {
"type": "array",
"items": {
"type": "string"
}
},
"not_supplied": {
"type": "array",
"items": {
"type": "string"
}
},
"discrepancies": {
"type": "array",
"items": {
"type": "string"
}
},
"missing_checks": {
"type": "array",
"items": {
"type": "string"
}
},
"identifier_outcome": {
"type": "string"
},
"unavailable_checks": {
"type": "array",
"items": {
"type": "string"
}
}
},
"additionalProperties": false
}
},
"test_only": {
"type": "boolean",
"const": false
},
"schema_version": {
"type": "string",
"const": "1.0"
}
},
"additionalProperties": false
}
}
}
}
}
},
"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"
}
}
}
}
},
"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.
0.05USDC≈ $0.05 USD
on Base · exact scheme
Pay 0.05 USDC on Base to 0xce53…d1342. The signed payment is good for 1 minute.
- Paid to
- 0xce53…d1342
- USD Coin contract
- 0x8335…02913
- Payment window
- 1 minute
- As published
- 50000 smallest units
The catalog’s raw entry
[
{
"asset": "0x833589fCD6eDb6E08f4c7C32D4f71b54bdA02913",
"extra": {
"name": "USD Coin",
"version": "2",
"paymentFlow": "authorization",
"assetTransferMethod": "eip3009"
},
"payTo": "0xce53bde2C7a639fc5526AC006a8A7866625d1342",
"amount": "50000",
"scheme": "exact",
"network": "eip155:8453",
"maxTimeoutSeconds": 60
}
]Extensions
{
"bazaar": {
"info": {
"input": {
"body": {
"references": [
{
"id": "forest-mutation",
"doi": "10.1023/a:1010933404324",
"year": 2002
}
]
},
"type": "http",
"method": "POST",
"bodyType": "json"
},
"output": {
"type": "json",
"example": {
"records": [
{
"id": "forest-mutation",
"doi": "10.1023/a:1010933404324",
"fields": [
{
"field": "title",
"status": "not_supplied",
"supplied": null,
"retrieved": [
"Random Forests"
]
},
{
"field": "authors",
"status": "not_supplied",
"supplied": null,
"retrieved": [
{
"given": "Leo",
"family": "Breiman"
}
]
},
{
"field": "year",
"status": "disagree",
"supplied": 2002,
"retrieved": {
"issued": [
[
2001,
10
]
],
"published": [
[
2001,
10
]
],
"published-print": [
[
2001,
10
]
]
}
}
],
"provenance": {
"url": "https://api.crossref.org/works/10.1023%2Fa%3A1010933404324",
"source": "Crossref",
"retrieved_at": "2026-09-09T16:16:30.570Z"
},
"ambiguities": [],
"not_supplied": [
"title",
"authors"
],
"discrepancies": [
"year"
],
"missing_checks": [],
"identifier_outcome": "found",
"unavailable_checks": []
}
],
"test_only": false,
"schema_version": "1.0"
}
}
},
"schema": {
"type": "object",
"$schema": "https://json-schema.org/draft/2020-12/schema",
"required": [
"input"
],
"properties": {
"input": {
"type": "object",
"required": [
"type",
"method",
"bodyType",
"body"
],
"properties": {
"body": {
"type": "object",
"$schema": "https://json-schema.org/draft/2020-12/schema",
"required": [
"references"
],
"properties": {
"references": {
"type": "array",
"items": {
"type": "object",
"anyOf": [
{
"required": [
"title"
]
},
{
"required": [
"authors"
]
},
{
"required": [
"year"
]
}
],
"required": [
"id",
"doi"
],
"properties": {
"id": {
"type": "string",
"maxLength": 64,
"minLength": 1
},
"doi": {
"type": "string",
"pattern": "^10\\.\\d{4,9}\\/[^\\s\\x00-\\x20?#%\\\\]+$",
"maxLength": 200
},
"year": {
"type": "integer",
"maximum": 9999,
"minimum": 1
},
"title": {
"type": "string",
"maxLength": 2000,
"minLength": 1
},
"authors": {
"type": "array",
"items": {
"type": "object",
"required": [
"family"
],
"properties": {
"given": {
"type": "string",
"maxLength": 200,
"minLength": 1
},
"family": {
"type": "string",
"maxLength": 200,
"minLength": 1
}
},
"additionalProperties": false
},
"maxItems": 40,
"minItems": 1
}
},
"additionalProperties": false
},
"maxItems": 10,
"minItems": 1
}
},
"description": "One to ten DOI-bearing records, each with at least one title, authors or year. Record IDs must be unique within a batch (case-sensitive); JSON Schema does not enforce uniqueness by id. DOIs, titles and author names are trimmed before runtime validation; DOIs are lowercased. Whitespace-only titles/names are rejected. application/json is required; the raw UTF-8 body is limited to 32768 bytes and a five-second input deadline.",
"additionalProperties": false
},
"type": {
"type": "string",
"const": "http"
},
"method": {
"enum": [
"POST"
],
"type": "string"
},
"bodyType": {
"enum": [
"json",
"form-data",
"text"
],
"type": "string"
}
},
"additionalProperties": false
},
"output": {
"type": "object",
"required": [
"type"
],
"properties": {
"type": {
"type": "string"
},
"example": {
"type": "object",
"$schema": "https://json-schema.org/draft/2020-12/schema",
"required": [
"schema_version",
"test_only",
"records"
],
"properties": {
"records": {
"type": "array",
"items": {
"type": "object",
"required": [
"id",
"doi",
"identifier_outcome",
"provenance",
"fields",
"discrepancies",
"ambiguities",
"missing_checks",
"unavailable_checks",
"not_supplied"
],
"properties": {
"id": {
"type": "string"
},
"doi": {
"type": "string"
},
"fields": {
"type": "array",
"items": {
"type": "object",
"required": [
"field",
"supplied",
"retrieved",
"status"
],
"properties": {
"field": {
"enum": [
"title",
"authors",
"year"
],
"type": "string"
},
"status": {
"enum": [
"agree",
"disagree",
"ambiguous",
"missing",
"unavailable",
"not_supplied"
],
"type": "string"
},
"supplied": {
"anyOf": [
{
"type": "string"
},
{
"type": "number"
},
{
"type": "null"
},
{
"type": "array",
"items": {
"type": "string"
}
},
{
"type": "array",
"items": {
"type": "object",
"properties": {
"given": {
"type": "string",
"maxLength": 200
},
"family": {
"type": "string",
"maxLength": 200
}
},
"additionalProperties": false
}
},
{
"type": "object",
"propertyNames": {
"type": "string"
},
"additionalProperties": {
"type": "array",
"items": {
"type": "array",
"items": {
"type": "number"
}
}
}
}
]
},
"retrieved": {
"anyOf": [
{
"type": "string"
},
{
"type": "number"
},
{
"type": "null"
},
{
"type": "array",
"items": {
"type": "string"
}
},
{
"type": "array",
"items": {
"type": "object",
"properties": {
"given": {
"type": "string",
"maxLength": 200
},
"family": {
"type": "string",
"maxLength": 200
}
},
"additionalProperties": false
}
},
{
"type": "object",
"propertyNames": {
"type": "string"
},
"additionalProperties": {
"type": "array",
"items": {
"type": "array",
"items": {
"type": "number"
}
}
}
}
]
}
},
"additionalProperties": false
}
},
"provenance": {
"type": "object",
"required": [
"source",
"url",
"retrieved_at"
],
"properties": {
"url": {
"type": "string"
},
"source": {
"type": "string",
"const": "Crossref"
},
"retrieved_at": {
"type": [
"string",
"null"
]
}
},
"additionalProperties": false
},
"ambiguities": {
"type": "array",
"items": {
"type": "string"
}
},
"not_supplied": {
"type": "array",
"items": {
"type": "string"
}
},
"discrepancies": {
"type": "array",
"items": {
"type": "string"
}
},
"missing_checks": {
"type": "array",
"items": {
"type": "string"
}
},
"identifier_outcome": {
"type": "string"
},
"unavailable_checks": {
"type": "array",
"items": {
"type": "string"
}
}
},
"additionalProperties": false
}
},
"test_only": {
"type": "boolean",
"const": false
},
"schema_version": {
"type": "string",
"const": "1.0"
}
},
"additionalProperties": false
}
}
}
}
}
},
"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"
}
}
}
}
}Provenance
- Seen in the source catalog
- 2026-09-22 18:56Z
- Last indexed by Roundhouse
- 2026-09-23 13:10Z
- Last enriched (probe, favicon, geo)
- 2026-09-19 20:45Z
- x402 version
- 2
- Max timeout
- 60s
- Liveness probe
- HTTP 402
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. 6 snapshots so far. Verified volume counts only settlements with an on-chain EIP-3009 marker.
Show the promptHide the prompt
Using Roundhouse, look up the x402 service Penny Army Reference Metadata 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=Penny%20Army%20Reference%20Metadata' 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://penny-army-reference-mainnet.spruceboundgranitestudio.workers.dev/v1/compare-reference-metadata, 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.