x402-gated premium API endpoint on Base network, pay-per-request with USDC.
What it does
lowpaymentfee.com hosts a collection of x402-protocol pay-per-request API endpoints spanning data analytics, AI/ML inference, finance/crypto data, and infrastructure utilities. The specific endpoint at `/api/resource/5` is listed as "Premium API Access" and returns a 402 challenge requiring payment in USDC on the Base network.
The x402 challenge for this endpoint specifies a maximum amount of 20,000 units of USDC (asset 0x833589fCD6eDb6E08f4c7C32D4f71b54bdA02913 on Base), using the "exact" payment scheme. The endpoint accepts HTTP POST requests and returns application/json responses. No API keys or rate limits are advertised — access is gated purely by the x402 payment header.
However, the specific functionality behind `/api/resource/5` is not documented. The site's landing page lists numerous other endpoints (analytics, AI, finance, utilities) all priced at $0.02 per request, but `/api/resource/5` does not appear among them. The docs, pricing, and README pages returned only a "Connect wallet" prompt with no substantive content. Without documentation of what this endpoint actually does or what input it expects, its practical utility is unclear.
Capabilities
Use cases
- —Accessing a premium API resource via x402 micropayment on Base
- —Demonstrating x402 protocol payment flows
- —Agent-initiated pay-per-call API consumption
Fit
Best for
- —Developers experimenting with x402 payment protocol
- —Agents that can sign USDC transactions on Base
- —Use cases requiring keyless, pay-per-request API access
Not for
- —Users who need documented, well-specified API contracts
- —Production workloads requiring SLAs or guaranteed uptime
- —Users without a Base-network USDC wallet
Quick start
curl -X POST https://lowpaymentfee.com/api/resource/5
# Returns 402 with X-PAYMENT challenge header
# Attach a valid x402 payment header (USDC on Base) to access the resourceExample
Response
{
"error": "X-PAYMENT header is required",
"accepts": [
{
"asset": "0x833589fCD6eDb6E08f4c7C32D4f71b54bdA02913",
"payTo": "0x1A2B13E97f5F837C8F9FA1F95a1484B7C70d85F3",
"scheme": "exact",
"network": "base",
"mimeType": "application/json",
"resource": "https://lowpaymentfee.com/api/resource/5",
"description": "Premium API Access",
"maxAmountRequired": "20000",
"maxTimeoutSeconds": 300
}
],
"x402Version": 1
}Endpoint
Quality
The endpoint is live and returns a valid 402 challenge, but there is no documentation of what `/api/resource/5` actually does, no input/output schema beyond the 402 challenge, and the docs/pricing/README pages are empty. The endpoint doesn't appear in the site's own listed API catalog, making its purpose entirely opaque.
Warnings
- —The specific endpoint /api/resource/5 is not listed among the site's documented APIs — its functionality is unknown.
- —All documentation pages (docs, pricing, README) returned only 'Connect wallet' with no content.
- —maxAmountRequired of 20000 USDC units — actual dollar cost is unclear without knowing the token decimals context (USDC has 6 decimals, so this would be $0.02).
- —No input schema or example payloads are available for this endpoint.
Citations
- —The endpoint returns a 402 challenge with x402Version 1, requiring USDC payment on Base networkhttps://lowpaymentfee.com/api/resource/5
- —The site advertises $0.02 per request pricing with no API keys, no rate limits, and instant accesshttps://lowpaymentfee.com
- —The USDC asset address is 0x833589fCD6eDb6E08f4c7C32D4f71b54bdA02913 on Basehttps://lowpaymentfee.com/api/resource/5
- —The site lists endpoints for analytics, AI/ML, finance, and utility categories but /api/resource/5 is not among themhttps://lowpaymentfee.com