payment-ready until 2026-10-06
A corpus of 3,029 public-domain audiobooks by 1,822 authors, with original editorial descriptions and 1,644 machine transcripts across 12 languages (ar, bg, de, en, es, fr, hi, ja, ko, pt, ru, zh). Four x402-metered endpoints: the full catalogue, per-book records, substring search over title and author, and full transcript text per book per language. The audio is public-domain LibriVox narration and is NOT sold here; it is free from us and from LibriVox. What is metered is our own work: the catalogue metadata, the editorial essays, and the transcripts and translations. Human-facing pages and search-engine crawlers are never charged. Terms: https://supremeaudiobooks.com/licensing
Pay from $0.001 to $0.05 per request in USDC on Base, settled onchain via the x402 protocol, no signup, no API key needed.
measured since 2026-08-26 (start of our harvest window) · $0 all-time · last settled 2026-09-25
VERDICT
ranking generation 3solid 89/100 #3 of 41 in Content by measured score
What the score read on this service: status online, 100% uptime 30d, 705ms response p95, x402 compliance 14 of 14, $0.001 price against the category, on-chain traction measured. 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 Content, 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 41 listings, this one among them. That set is wider than the 41 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 CONTENT
Other Content 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 |
|---|---|---|---|---|
| 21millionpixels.art | solid | 91 | 100% | $49.64 |
| ForgeMesh Library | solid | 89 | 99.4% | $0.06 |
| Skim | solid | 88 | 99.9% | $0.89 |
| penny402 | solid | 88 | 100% | $0.13 |
| Busker | solid | 88 | 100% | $0.05 |
ASSESSMENT
updated 58m 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 · latest daily rollup
- 100%
- uptime 7d
- 100%
- uptime 30d
- 100%
- uptime 90d
- 100%
- response p95
- 705ms
- avg response
- 333ms
- total checks
- 2,784
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 $0.001 to $0.05 (p6 in Content)
- price (min)
- $0.001
- price (max)
- $0.05
- category percentile (min)
- p6 in Content
- category percentile (max)
- p40 in Content
- endpoints / prices
- 3 / 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
- 342d
- registrar
- Spaceship, Inc.
- hosting
- custom
- domain created
- 2025-10-17
Identity facts, not a risk score.
traction $0.00 30d · 0 buyers
- volume 30d
- $0.00
- buyers 30d
- 0
- settlements 30d
- 0
- measured since
- 2026-08-26 (start of our harvest window)
- last settlement
- 2026-09-25
- top buyer share
- -
- trend 7d vs 30d
- -
- networks
- eip155:8453
- volume all-time
- $0
- settlements all-time
- 0
- median settlement 30d
- -
- max settlement 30d
- -
- settled via
- -
Conservative undercount: only USDC settlements via facilitators we measure are counted. A measured floor, not an estimate.
Top buyer share is part of the ranking score: a higher share lowers the traction part of the score, by up to half when one address holds all 30d volume.
WHAT IT DOES
ai-derivedNo AI synthesis has been produced for this service yet.
ENDPOINTS
| METHOD | PATH | DESCRIPTION | PRICE | NETWORK | ASSET | 402 CHANNEL |
|---|---|---|---|---|---|---|
| GET | /api/v1/books/a_christmas_carol | Metadata for a single audiobook | $0.001 | Base | USDC | header |
| GET | /api/v1/catalog | Complete Supreme Audiobooks catalogue as JSON | $0.05 | Base | USDC | header |
| GET | /api/v1/transcripts/a_christmas_carol | Full transcript text for one audiobook, one language | $0.01 | Base | USDC | header |
REQUEST / RESPONSE EXAMPLE
An unpaid request to GET /api/v1/books/a_christmas_carol returns HTTP 402 with the payment terms. Settle onchain via your facilitator, then retry with the X-Payment header.
curl -i 'https://supremeaudiobooks.com/api/v1/books/a_christmas_carol'
// 402 response (captured by monitor) · 3 payloads · click to expand
[
{
"error": "X-PAYMENT header is required",
"accepts": [
{
"asset": "0x833589fCD6eDb6E08f4c7C32D4f71b54bdA02913",
"extra": {
"name": "USD Coin",
"version": "2",
"assetTransferMethod": "eip3009"
},
"payTo": "0x76e69B782A6ad5d0D68CB8e47C42A4c00E42B84E",
"amount": "50000",
"scheme": "exact",
"network": "eip155:8453",
"maxTimeoutSeconds": 60
}
],
"resource": {
"url": "https://supremeaudiobooks.com/api/v1/catalog",
"tags": [
"audiobooks",
"catalog",
"public-domain"
],
"mimeType": "application/json",
"description": "Complete Supreme Audiobooks catalogue as JSON",
"serviceName": "Supreme Audiobooks"
},
"x402Version": 2
},
{
"error": "X-PAYMENT header is required",
"accepts": [
{
"asset": "0x833589fCD6eDb6E08f4c7C32D4f71b54bdA02913",
"extra": {
"name": "USD Coin",
"version": "2",
"assetTransferMethod": "eip3009"
},
"payTo": "0x76e69B782A6ad5d0D68CB8e47C42A4c00E42B84E",
"amount": "1000",
"scheme": "exact",
"network": "eip155:8453",
"maxTimeoutSeconds": 60
}
],
"resource": {
"url": "https://supremeaudiobooks.com/api/v1/books/a_christmas_carol",
"tags": [
"audiobooks",
"catalog",
"public-domain"
],
"mimeType": "application/json",
"description": "Metadata for a single audiobook",
"serviceName": "Supreme Audiobooks"
},
"x402Version": 2
},
{
"error": "X-PAYMENT header is required",
"accepts": [
{
"asset": "0x833589fCD6eDb6E08f4c7C32D4f71b54bdA02913",
"extra": {
"name": "USD Coin",
"version": "2",
"assetTransferMethod": "eip3009"
},
"payTo": "0x76e69B782A6ad5d0D68CB8e47C42A4c00E42B84E",
"amount": "10000",
"scheme": "exact",
"network": "eip155:8453",
"maxTimeoutSeconds": 60
}
],
"resource": {
"url": "https://supremeaudiobooks.com/api/v1/transcripts/a_christmas_carol",
"tags": [
"audiobooks",
"catalog",
"public-domain"
],
"mimeType": "application/json",
"description": "Full transcript text for one audiobook, one language",
"serviceName": "Supreme Audiobooks"
},
"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/supreme-audiobooks/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 3 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 2026-08-26 · last up 2026-09-29
- 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
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