Pay-per-call API platform on Base network via x402 — $0.02/request in USDC.
What it does
lowpaymentfee.com is a pay-per-request API platform that uses the x402 protocol to accept USDC payments on the Base network. The specific endpoint `/api/v1/charges/90` is listed as "Premium API Access" and returns a 402 challenge requesting up to 20,000 base units of USDC (0.02 USD) per call. The platform advertises no API keys, no rate limits, and instant access — you simply attach an X-PAYMENT header with a valid x402 payment to use any endpoint.
The broader platform offers 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.
However, the specific functionality behind `/api/v1/charges/90` ("Premium API Access") is not documented beyond its name. The docs, pricing, and README pages all render only a "Connect wallet" prompt with no additional technical documentation, schemas, or example payloads. Without paying for a request, it is unclear what data this particular endpoint returns or what input it expects beyond a POST request with a JSON content type. The platform is live and the x402 challenge is well-formed, but the lack of documentation is a significant gap.
Capabilities
Use cases
- —Programmatic access to premium API data without subscription or API key management
- —Agent-driven workflows that need on-demand API calls settled in USDC on Base
- —Testing x402 payment protocol integrations with a low-cost endpoint
Fit
Best for
- —Developers exploring x402 pay-per-call patterns
- —AI agents needing keyless, instant API access
- —Low-volume or sporadic API consumers who want no commitments
Not for
- —Users who need detailed API documentation or schemas before purchasing
- —High-volume consumers who would benefit from bulk pricing or subscriptions
- —Anyone without a Base-network USDC wallet
Quick start
curl -X POST https://lowpaymentfee.com/api/v1/charges/90 \
-H "Content-Type: application/json" \
-H "X-PAYMENT: <x402-payment-token>"Endpoint
Quality
The endpoint is live and returns a valid x402 402 challenge, but there is essentially no documentation: no OpenAPI spec, no request/response schemas, no examples, and no explanation of what 'Premium API Access' actually returns. The docs pages are empty beyond a wallet-connect prompt. The listing is effectively a stub.
Warnings
- —No documentation available — docs, pricing, and README pages only show 'Connect wallet'
- —The specific functionality of /api/v1/charges/90 ('Premium API Access') is completely undocumented
- —No request or response schema is provided; input/output format is unknown
- —No OpenAPI specification or API reference found
Citations
- —The endpoint returns a 402 challenge requesting up to 20,000 base units of USDC (asset 0x833589fCD6eDb6E08f4c7C32D4f71b54bdA02913) on Base networkhttps://lowpaymentfee.com/api/v1/charges/90
- —All endpoints are priced at $0.02 per request with no API keys, no rate limits, and instant accesshttps://lowpaymentfee.com
- —The platform offers endpoints in Data & Analytics, AI & ML, Finance & Web3, and Infrastructure categorieshttps://lowpaymentfee.com
- —Docs, pricing, and README pages render only a 'Connect wallet' prompthttps://lowpaymentfee.com/docs