x402basequality 0.35

x402-gated API platform on Base offering data, AI, finance, and utility endpoints at $0.02/request.

Price
0.02 USDC / call
Protocol
x402
Verified
no
Endpoint
https://lowpaymentfee.com/api/v1/carts/79

What it does

lowpaymentfee.com is an x402-protocol API marketplace that gates access to a variety of endpoints behind per-request USDC micropayments on the Base network. The platform advertises four categories of APIs: Data & Analytics (metrics, reports, data export, insights), AI & Machine Learning (sentiment analysis, text summarization, classification, embeddings), Finance & Web3 (price feeds, exchange rates, token quotes, gas estimates), and Infrastructure utilities (geocoding, validation, conversion, generation). All endpoints are priced at $0.02 per request with no API keys, no rate limits, and no minimum commitments required.

The specific endpoint at `/api/v1/carts/79` is labeled "Premium API Access" and returns a valid x402 challenge requesting payment in USDC (contract 0x8335…2913) on Base. The max amount required is 20,000 base units, which at 6 decimals for USDC equals $0.02 — consistent with the site's advertised pricing. Payment is made via the x402 exact scheme with a 300-second timeout. The endpoint accepts POST requests and returns application/json.

Documentation beyond the landing page is essentially empty — the /docs, /api, /pricing, and /README pages all render only a "Connect wallet" prompt with no substantive content. There is no OpenAPI spec, no request/response schema documentation, and no examples of what the "Premium API Access" endpoint actually returns. The endpoint name ("carts/79") suggests it may be a shopping-cart or catalog resource, but this is speculative. Without documentation or sample responses, the actual functionality behind this endpoint remains unclear.

Capabilities

x402-paymentusdc-micropaymentbase-networkper-request-billingno-api-keyjson-responsepost-method

Use cases

  • —Programmatic access to pay-per-call API endpoints without managing API keys or subscriptions
  • —Agent-driven workflows that need on-demand API access settled via crypto micropayments
  • —Exploring x402-protocol integration for building payment-gated services

Fit

Best for

  • —Developers experimenting with x402 payment protocol on Base
  • —Agents that can settle USDC micropayments per request
  • —Use cases requiring keyless, commitment-free API access

Not for

  • —Users who need detailed API documentation or guaranteed SLAs before integrating
  • —High-volume production workloads where per-request crypto settlement adds latency
  • —Users without a Base-network USDC wallet

Quick start

# 1. Send a POST to get the 402 challenge
curl -X POST https://lowpaymentfee.com/api/v1/carts/79
# 2. Parse the x402 challenge from the response
# 3. Sign a USDC payment on Base for 20000 base units ($0.02)
# 4. Resend the POST with the X-PAYMENT header containing the signed payment

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/carts/79",
      "description": "Premium API Access",
      "maxAmountRequired": "20000",
      "maxTimeoutSeconds": 300
    }
  ],
  "x402Version": 1
}

Endpoint

URLhttps://lowpaymentfee.com/api/v1/carts/79
Transporthttp
Protocolx402
Pay to0x1A2B13E97f5F837C8F9FA1F95a1484B7C70d85F3
CurrencyUSD COIN

Quality

0.35/ 1.00

The endpoint is live and returns a valid x402 challenge with clear pricing ($0.02 USDC on Base). However, there is no documentation, no OpenAPI spec, no request/response schema, and no explanation of what the 'carts/79' endpoint actually does or returns after payment. The site's docs pages are all empty 'Connect wallet' stubs.

Warnings

  • —No documentation available — /docs, /api, /pricing, and /README pages are all empty stubs
  • —No OpenAPI or schema describing request parameters or response format
  • —The endpoint path '/api/v1/carts/79' does not match any of the advertised API categories on the landing page, making its actual functionality unclear
  • —No examples of successful (paid) responses available

Citations

Provenance

Indexed fromx402_bazaar
Enriched2026-04-18 23:36:01Z · anthropic/claude-opus-4.6 · v2
First seen2026-04-18
Last seen2026-04-23

Agent access

JSONhttps://clawmart.sh/api/listings/e5DLTJ