Pay-per-call API platform on Base network via x402 — $0.02/request in USDC.
What it does
lowpaymentfee.com is an x402-enabled API platform that offers a broad catalog of endpoints spanning data analytics, AI/ML inference, finance/Web3 data, and utility services. Every endpoint costs $0.02 per request, paid in USDC on the Base network with no API keys, no rate limits, and no commitments required. The x402 protocol handles payment inline: callers attach a payment header and the server fulfills the request upon verification.
The specific endpoint at `/api/v1/transactions/309` is listed as "Premium API Access" and returns an x402 challenge requesting up to 20,000 base units of USDC (0x8335…2913 on Base). Since USDC uses 6 decimals, this equals $0.02 per call — consistent with the site's advertised flat pricing. Payment is settled to address 0x1A2B13E97f5F837C8F9FA1F95a1484B7C70d85F3 with a 300-second timeout.
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 spec, no request/response schema documentation, and no examples of what this particular endpoint accepts or returns. The site's landing page lists many endpoint categories but provides no detail on input parameters or response formats. As a result, it is unclear what data or functionality `/api/v1/transactions/309` actually provides — the "Premium API Access" label is generic and uninformative.
Capabilities
Use cases
- —Accessing premium data or transaction information via a single paid HTTP call
- —Integrating pay-per-use API access into autonomous agents without pre-registration
- —Testing x402 payment flows on Base network
Fit
Best for
- —Developers experimenting with x402 payment protocol
- —Agents needing keyless, pay-per-call API access on Base
- —Projects wanting USDC-settled micropayment APIs
Not for
- —Users who need detailed API documentation or OpenAPI specs before integrating
- —High-volume use cases where $0.02/request adds up without bulk discounts
- —Anyone requiring guaranteed SLAs or support
Quick start
curl -X POST https://lowpaymentfee.com/api/v1/transactions/309 \
-H "Content-Type: application/json" \
-H "X-PAYMENT: <x402-payment-token>"Endpoint
Quality
The endpoint is live and returns a valid x402 challenge with clear pricing, but there is zero documentation on what the endpoint actually does, no request/response schemas, and no examples. The 'Premium API Access' label is generic. All doc pages render only 'Connect wallet' with no content.
Warnings
- —No documentation available — /docs, /pricing, /api, and /README all show only 'Connect wallet'
- —No OpenAPI spec or request/response schema provided
- —The purpose of /api/v1/transactions/309 ('Premium API Access') is entirely unclear
- —Cannot verify what data or functionality this endpoint returns
Citations
- —Flat pricing of $0.02 per request, no API keys, no rate limitshttps://lowpaymentfee.com
- —x402 challenge requests maxAmountRequired of 20000 base units of USDC on Base (= $0.02)https://lowpaymentfee.com/api/v1/transactions/309
- —USDC asset contract on Base: 0x833589fCD6eDb6E08f4c7C32D4f71b54bdA02913https://lowpaymentfee.com/api/v1/transactions/309
- —Site lists endpoints across Data & Analytics, AI & ML, Finance & Web3, and Infrastructure categorieshttps://lowpaymentfee.com