Barcode and ISBN check digit validator

caution grade B Base found on thirdweb found on PayAI confidence 0.71
https://x402-catalog-history.ai-business-surface.workers.dev/barcode
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Advertised description
Barcode check digit validator in one GET: EAN-13, UPC-A, EAN-8, ISBN-10 and ISBN-13 — returns the symbology, the check digit it carries, the expected check digit and whether the number is valid. curl: GET…Show more ▾Show less ▴Barcode check digit validator in one GET: EAN-13, UPC-A, EAN-8, ISBN-10 and ISBN-13 — returns the symbology, the check digit it carries, the expected check digit and whether the number is valid. curl: GET /barcode?code=9780306406157 (spaces and hyphens are ignored). Response: {"normalized":"9780306406157","symbology":"isbn-13","length":13,"check_digit":"7","expected_check_digit":"7","valid":true,"gs1_prefix":"978","isbn":{"format":"isbn-13","prefix":"978"}}. ISBN-10 accepts a trailing X. The verdict is check-digit arithmetic on the number you pass, not a registry lookup: a valid code does not prove that the product or book exists. Computed inside the Worker from the input; no upstream call, no account, no key. 0.001 USDC, one GET, one delivery. A purchase is two calls by design: this first call returns 402 with the price and the payment terms, and you then repeat the same request with the PAYMENT-SIGNATURE header to receive the 200 delivery.
(Provider-supplied: an unverified claim, not checked by us. The trust grade above is our independent measurement.)
30-day uptime
100.0%
Avg latency (EU)
1134 ms
slow · measured from a single EU vantage point; includes network round-trip distance to the endpoint; a geographically distant endpoint reads slower even when its server is fast, so it is only lightly weighted in the score
Confidence
0.71
full-density score
Advertised price
$0.001
USDC
Price stability
Stable
last 30 days
Probes (30d)
57
full record · up to 48/day
More details ▾
Endpoint ID270029
Pay on Base$0.001 USDC · to 0x6f60…89c3 ↗
First seen2026-10-18
Last probed2026-10-30
Statuslisted
Snapshot computed2026-10-30 08:47 UTC (free snapshot, recomputed at least every 24h)
Why this verdict?2 warnings
A wallet payment page opens first; approve the USDC payment and the full JSON report loads right in your browser. Want a taste first? Read a free full sample report.
This page is the free cached snapshot (computed 2 hours ago, refreshed at least every 24h). Here's what the paid API adds.
  • ✓Live re-probe at decision time
    The score is computed the moment you ask, not up to 24h ago.
  • ✓Instant snapshot refresh
    Every paid call rewrites this page, the badge and the card immediately.
  • ✓The full “why”, machine-readable
    Confidence band, component breakdown, every risk flag with its evidence.
  • ✓On-chain settlement proof
    Real USDC volume and distinct payers behind the pay-to wallet.
  • ✓90-day raw history
    Every listing, price and payTo change, every probe result.
  • ✓Ranked better alternatives
    Higher-scored endpoints serving the same function, when they exist.
  • ✓Change & liveness alerts
    PayTo/price moves, spec regressions, downtime; 5-minute probes while watched.
$npx -y x402-trust-mcpGive your agents the tools to do all of this for you, with one install. Agents use the x402_trust_score MCP tool or POST /v1/x402-trust directly (pay-per-call over x402, from $0.005).