Pay-per-call premium API access on Base via x402 — $0.02/request in USDC.
What it does
This endpoint at lowpaymentfee.com provides "Premium API Access" via the x402 payment protocol. The probed endpoint (/api/v1/payments/237) returns a valid 402 challenge requesting payment in USDC on the Base network. The site advertises a broad catalog of API endpoints spanning data & analytics, 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 priced at $0.02 per request.
The x402 challenge for this specific endpoint specifies a maxAmountRequired of 20000 base units of USDC (0x833589fCD6eDb6E08f4c7C32D4f71b54bdA02913 on Base, 6 decimals), which equals $0.02 USD. Payment is made via the "exact" scheme to address 0x1A2B13E97f5F837C8F9FA1F95a1484B7C70d85F3 with a 300-second timeout. No API keys or rate limits are advertised; access is instant upon payment.
However, the specific functionality behind the /api/v1/payments/237 path is unclear — the description simply says "Premium API Access" without detailing what data or service is returned. The docs, pricing, and API pages all render only a "Connect wallet" prompt with no further documentation. There is no OpenAPI spec, no request/response schema beyond the x402 outputSchema stub, and no examples of what a successful response looks like. The site appears to be a demonstration or early-stage platform for x402-gated microservices.
Capabilities
Use cases
- —Agents that need on-demand API access without pre-registration or API keys
- —Programmatic micropayment-gated service consumption on Base L2
- —Testing x402 payment protocol integrations with a low-cost endpoint
Fit
Best for
- —Developers exploring x402 payment protocol integration
- —AI agents needing keyless, pay-per-call API access
- —Low-cost per-request microservice consumption on Base
Not for
- —Production workloads requiring documented request/response schemas
- —Users who need detailed API documentation or SLA guarantees
- —Anyone without a Base-compatible USDC wallet
Quick start
curl -X POST https://lowpaymentfee.com/api/v1/payments/237 \
-H "Content-Type: application/json" \
-H "X-PAYMENT: <x402-payment-header>"Endpoint
Quality
The endpoint is live and returns a valid x402 402 challenge, confirming it accepts USDC on Base at $0.02/request. However, there is no documentation, no OpenAPI spec, no request/response examples, and the specific functionality of /api/v1/payments/237 is undescribed. The docs and other pages render only wallet-connect prompts. This is effectively a stub listing.
Warnings
- —No documentation available — docs, pricing, and API pages all show only 'Connect wallet'
- —No OpenAPI or request/response schema provided
- —The specific functionality of /api/v1/payments/237 is not described beyond 'Premium API Access'
- —Cannot verify what data or service is actually returned upon successful payment
- —Site may be a demo or early-stage platform
Citations
- —The endpoint returns a 402 challenge requesting 20000 base units of USDC on Base (=$0.02)https://lowpaymentfee.com/api/v1/payments/237
- —The site advertises $0.02/request pricing with no API keys, no rate limits, and instant accesshttps://lowpaymentfee.com
- —USDC asset contract on Base is 0x833589fCD6eDb6E08f4c7C32D4f71b54bdA02913https://lowpaymentfee.com/api/v1/payments/237
- —Available API categories include Data & Analytics, AI & ML, Finance & Web3, and Infrastructurehttps://lowpaymentfee.com