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/transactions/41` is listed as "Premium API Access" and returns a 402 challenge requesting up to 20,000 base units of USDC (i.e., $0.02) per call. The platform advertises no API keys, no rate limits, and instant access — callers simply attach an X-PAYMENT header with a valid x402 payment proof.
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 listed at $0.02 per request. However, the specific endpoint probed here (`/api/v1/transactions/41`) does not clearly map to any of these advertised categories — its purpose beyond "Premium API Access" is not documented.
Documentation is extremely thin. The /docs, /pricing, /api, and /README pages all render only a "Connect wallet" prompt with no further content. There is no OpenAPI schema, no request/response examples, and no description of what data or functionality this particular transactions endpoint returns. The endpoint is live and responds with a well-formed x402 challenge, but the actual payload it delivers after payment is unknown.
Capabilities
Use cases
- —Accessing premium API data with per-request USDC micropayments on Base
- —Agent-driven API consumption without pre-registration or API keys
- —Programmatic pay-as-you-go access to analytics, AI, finance, or utility endpoints
Fit
Best for
- —Developers who want keyless, pay-per-use API access
- —AI agents with x402-compatible wallets on Base
- —Users who prefer crypto micropayments over subscription billing
Not for
- —Users who need detailed API documentation or OpenAPI specs before integrating
- —High-volume consumers who want bulk pricing or subscription discounts
- —Developers without a Base-network USDC wallet
Quick start
# The endpoint requires an x402 X-PAYMENT header with a valid USDC payment proof on Base.
curl -X POST https://lowpaymentfee.com/api/v1/transactions/41 \
-H "Content-Type: application/json" \
-H "X-PAYMENT: <x402-payment-token>"Endpoint
Quality
The endpoint is live and returns a valid x402 challenge, but documentation is essentially nonexistent — all doc pages show only 'Connect wallet'. There is no OpenAPI schema, no request/response examples, and the purpose of this specific transactions/41 endpoint is undocumented. The listing is effectively a stub.
Warnings
- —No documentation available — /docs, /pricing, /api, and /README pages all render only 'Connect wallet'
- —No OpenAPI or schema describing request parameters or response format
- —The endpoint path /api/v1/transactions/41 does not match any of the advertised API categories on the homepage
- —Actual response payload after payment is completely unknown
Citations
- —The endpoint returns a 402 challenge requesting up to 20,000 base units of USDC ($0.02) on Base networkhttps://lowpaymentfee.com/api/v1/transactions/41
- —The platform advertises $0.02/request pricing with no API keys, no rate limits, and instant accesshttps://lowpaymentfee.com
- —USDC asset contract on Base: 0x833589fCD6eDb6E08f4c7C32D4f71b54bdA02913https://lowpaymentfee.com/api/v1/transactions/41
- —The platform lists endpoints across Data & Analytics, AI & ML, Finance & Web3, and Infrastructure categorieshttps://lowpaymentfee.com
- —Documentation pages (/docs, /pricing, /api, /README) render only 'Connect wallet'https://lowpaymentfee.com/docs