Pay-per-call premium API access on Base via x402 — $0.02/request in USDC.
What it does
lowpaymentfee.com hosts a collection of pay-per-request API endpoints gated by the x402 protocol on the Base network. This specific endpoint (`/api/v1/invoices/7`) is listed as "Premium API Access" and accepts payment in USDC (contract 0x8335…2913 on Base) at a maximum cost of 20,000 base units, which equals $0.02 per request (USDC uses 6 decimals). The payment scheme is "exact," meaning the caller pays a fixed amount per call with no subscription or API key required.
The broader lowpaymentfee.com platform advertises endpoints across four categories: 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.
Documentation is extremely sparse — the /docs, /api, /pricing, and /README pages all render only a "Connect wallet" prompt with no further technical detail. There is no OpenAPI spec, no request/response schema documentation, and no example payloads available. The specific purpose of `/api/v1/invoices/7` (as opposed to the other listed endpoints) is unclear; the name "Premium API Access" is generic and does not describe what data or functionality is returned. Callers should expect to experiment or contact the provider for details.
Capabilities
Use cases
- —Accessing premium data or services with per-request USDC micropayments on Base
- —Agent-driven API consumption without API key management
- —Testing x402 payment protocol integrations against a live endpoint
Fit
Best for
- —Developers experimenting with x402 payment-gated APIs
- —Agents that need keyless, pay-as-you-go API access on Base
- —Low-volume consumers who want no subscription commitments
Not for
- —Users who need detailed API documentation or guaranteed SLAs
- —High-volume production workloads requiring well-documented schemas and error handling
- —Anyone without a Base-compatible USDC wallet
Quick start
curl -X POST https://lowpaymentfee.com/api/v1/invoices/7 \
-H "Content-Type: application/json" \
-H "X-PAYMENT: <x402-payment-token>"Endpoint
Quality
The endpoint is live (402 challenge confirmed) and pricing is clear ($0.02 USDC on Base), but there is zero documentation on what the endpoint actually returns, no OpenAPI spec, no request/response schemas, and no examples. The /docs and other pages are empty beyond a wallet connect prompt. This is effectively a stub listing.
Warnings
- —No OpenAPI or schema documentation available — endpoint behavior is unknown
- —All documentation pages (/docs, /api, /pricing, /README) render only 'Connect wallet' with no content
- —The specific purpose of /api/v1/invoices/7 ('Premium API Access') is not described anywhere
- —No request body schema or response schema is documented
Citations
- —Endpoint returns 402 with x402 challenge advertising USDC on Base at maxAmountRequired 20000https://lowpaymentfee.com/api/v1/invoices/7
- —All endpoints priced at $0.02/request with no API keys, no rate limits, instant access on Base networkhttps://lowpaymentfee.com
- —Platform offers endpoints in Data & Analytics, AI & ML, Finance & Web3, and Infrastructure categorieshttps://lowpaymentfee.com
- —USDC asset contract on Base is 0x833589fCD6eDb6E08f4c7C32D4f71b54bdA02913https://lowpaymentfee.com/api/v1/invoices/7