x402basequality 0.35

x402-gated premium API endpoint on Base, pay-per-call with USDC.

Price
0.02 USDC / call
Protocol
x402
Verified
no
Endpoint
https://lowpaymentfee.com/api/v1/cards/31

What it does

This endpoint at `/api/v1/cards/31` is part of the lowpaymentfee.com platform, a collection of x402-protocol pay-per-request APIs spanning data analytics, AI/ML inference, finance/Web3, and infrastructure utilities. The specific `/api/v1/cards/31` resource is labeled "Premium API Access" but its exact functionality is not documented beyond that title — it is one of many endpoints on the platform, all gated behind x402 micropayments settled in USDC on the Base network.

The x402 challenge confirms the endpoint is live and accepts POST requests. The maximum amount required is 20,000 base units of USDC (the asset at 0x8335… is Base USDC with 6 decimals), which equals $0.02 per request. The platform advertises uniform $0.02/request pricing across all endpoints, with no API keys, no rate limits, and no minimum commitments. Payment is made via the x402 `exact` scheme to the specified payTo address.

Because the crawled documentation pages (docs, api, pricing, README) all returned only a "Connect wallet" prompt with no further content, the actual input/output schema and behavior of this specific endpoint remain unknown. The platform lists categories like Data & Analytics, AI & ML, Finance & Web3, and Infrastructure, but `/api/v1/cards/31` does not appear in any of those listed routes, making its purpose unclear. Treat this as a stub listing until more documentation becomes available.

Capabilities

x402-paymentusdc-basepay-per-requestpost-endpointmicropayment-gated

Use cases

  • —Accessing a premium pay-per-call API resource without API keys or subscriptions
  • —Making micropayment-gated requests settled in USDC on Base
  • —Programmatic agent-driven API consumption via x402 protocol

Fit

Best for

  • —Developers wanting zero-signup, pay-as-you-go API access
  • —AI agents that can settle x402 micropayments on Base
  • —Users who prefer crypto-native per-request billing over subscriptions

Not for

  • —Users who need detailed documentation or guaranteed SLAs before integrating
  • —Anyone requiring non-crypto payment methods
  • —Use cases requiring known, well-documented input/output schemas

Quick start

# 1. Send a POST to discover the x402 payment challenge
curl -X POST https://lowpaymentfee.com/api/v1/cards/31
# Returns 402 with X-Payment challenge in JSON body
# 2. Construct and attach the X-PAYMENT header per x402 spec, then re-send the POST

Example

Response

{
  "error": "X-PAYMENT header is required",
  "accepts": [
    {
      "asset": "0x833589fCD6eDb6E08f4c7C32D4f71b54bdA02913",
      "extra": {
        "name": "USD Coin",
        "version": "2"
      },
      "payTo": "0x1A2B13E97f5F837C8F9FA1F95a1484B7C70d85F3",
      "scheme": "exact",
      "network": "base",
      "mimeType": "application/json",
      "resource": "https://lowpaymentfee.com/api/v1/cards/31",
      "description": "Premium API Access",
      "maxAmountRequired": "20000",
      "maxTimeoutSeconds": 300
    }
  ],
  "x402Version": 1
}

Endpoint

URLhttps://lowpaymentfee.com/api/v1/cards/31
Transporthttp
Protocolx402
Pay to0x1A2B13E97f5F837C8F9FA1F95a1484B7C70d85F3
CurrencyUSD COIN

Quality

0.35/ 1.00

The endpoint is confirmed live via a valid 402 challenge, and pricing is clear ($0.02/request in USDC on Base). However, the specific functionality of /api/v1/cards/31 is entirely undocumented — it doesn't appear in the site's listed endpoints, there is no input/output schema, and all documentation pages returned only 'Connect wallet' with no content. This is effectively a stub.

Warnings

  • —The endpoint /api/v1/cards/31 is not listed among the platform's documented API routes — its purpose is unknown.
  • —All documentation pages (docs, api, pricing, README) returned only 'Connect wallet' with no usable content.
  • —No input or output schema is available; the actual response payload after successful payment is unknown.
  • —The 'Premium API Access' label is generic and does not describe functionality.

Citations

Provenance

Indexed fromx402_bazaar
Enriched2026-04-19 02:48:33Z · anthropic/claude-opus-4.6 · v2
First seen2026-04-18
Last seen2026-04-23

Agent access

JSONhttps://clawmart.sh/api/listings/DTzWkC
x402-gated premium API endpoint on Base, pay-per-call with USDC. — Clawmart · Clawmart