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/39` 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 priced at $0.02 per request.
This particular endpoint (`/api/v1/transactions/39`) is labeled "Premium API Access" but its actual functionality is not documented beyond that label. The crawled docs, pricing, API, and README pages all rendered only a "Connect wallet" prompt with no additional content. Without further documentation or example responses, the exact data returned by this endpoint remains unclear.
Capabilities
Use cases
- —Programmatic access to premium API data with per-request USDC micropayments
- —Agent-driven workflows that need keyless, on-demand API access
- —Testing x402 payment protocol integrations on Base network
Fit
Best for
- —Developers or agents wanting frictionless pay-per-use API access without subscriptions
- —x402-compatible AI agents that can settle USDC on Base
- —Users who prefer crypto micropayments over traditional API key management
Not for
- —Users who need detailed API documentation or guaranteed SLAs before purchasing
- —High-volume consumers who would benefit from bulk pricing or subscriptions
- —Anyone without a Base-network USDC wallet or x402-compatible client
Quick start
curl -X POST https://lowpaymentfee.com/api/v1/transactions/39 \
-H "Content-Type: application/json" \
-H "X-PAYMENT: <x402-payment-proof>"Endpoint
Quality
The endpoint is live and returns a valid x402 402 challenge, confirming pricing and payment details. However, there is no documentation, no OpenAPI schema, no example request/response, and the actual functionality behind "Premium API Access" is entirely undocumented. The docs, pricing, API, and README pages all render only a wallet-connect prompt with no useful content.
Warnings
- —The exact functionality of /api/v1/transactions/39 ('Premium API Access') is undocumented — it is unclear what data or service it provides.
- —All documentation pages (docs, pricing, API, README) returned only 'Connect wallet' with no substantive content.
- —No OpenAPI spec, no request/response schemas, and no usage examples are available.
- —The endpoint name 'transactions/39' with a numeric ID suggests it may be a specific resource rather than a general-purpose API.
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/39
- —The platform advertises $0.02/request pricing with no API keys, no rate limits, and instant access on Base networkhttps://lowpaymentfee.com
- —The platform offers endpoints across Data & Analytics, AI & ML, Finance & Web3, and Infrastructure categorieshttps://lowpaymentfee.com
- —The USDC asset address is 0x833589fCD6eDb6E08f4c7C32D4f71b54bdA02913 on Basehttps://lowpaymentfee.com/api/v1/transactions/39