x402-gated premium API endpoint on Base, pay $0.02 per request in USDC.
What it does
This endpoint at `/api/v1/cards/78` is part of the lowpaymentfee.com platform, which offers a collection of x402-protocol pay-per-request APIs spanning data & analytics, AI & machine learning, finance & Web3, and infrastructure utilities. The specific resource at `/cards/78` is labeled "Premium API Access" but its exact functionality is not documented beyond that label. All endpoints on the platform share a uniform $0.02 per request pricing model, settled in USDC on the Base network via the x402 payment protocol.
The probe confirms the endpoint is live, returning a 402 challenge with `maxAmountRequired` of 20000 base units of USDC (0x8335…2913 on Base, 6 decimals), which equals $0.02. Payment is made via the `exact` scheme to address `0x1A2B13E97f5F837C8F9FA1F95a1484B7C70d85F3`. The endpoint accepts POST requests and returns `application/json`. No API keys or rate limits are advertised; access is granted purely through per-call x402 payment.
Documentation is extremely sparse. The landing page lists many endpoints but provides no request/response schemas, parameter descriptions, or usage examples. The `/docs`, `/pricing`, `/api`, and `/README` pages all render only a "Connect wallet" prompt with no additional content. Because the specific purpose of `/api/v1/cards/78` is unclear and no schema is provided, agents should treat this as a low-documentation endpoint whose actual behavior must be discovered empirically.
Capabilities
Use cases
- —Accessing a premium data resource with per-call USDC micropayments
- —Agent-driven API consumption without pre-registration or API keys
- —Exploring x402 payment protocol integration on Base
Fit
Best for
- —Developers experimenting with x402 pay-per-request protocols
- —Agents that can settle USDC payments on Base automatically
- —Use cases requiring keyless, commitment-free API access
Not for
- —Users needing well-documented APIs with clear request/response schemas
- —High-volume use cases where per-call pricing may add up without bulk discounts
- —Anyone who needs to understand the endpoint's exact functionality before paying
Quick start
curl -X POST https://lowpaymentfee.com/api/v1/cards/78 \
-H "Content-Type: application/json" \
-H "X-PAYMENT: <x402-payment-token>"Endpoint
Quality
The endpoint is live and returns a valid x402 challenge, but there is no documentation, no request/response schema, and the purpose of '/api/v1/cards/78' is entirely unclear. The docs pages are empty beyond a wallet-connect prompt. This is effectively a stub listing.
Warnings
- —The specific functionality of /api/v1/cards/78 ('Premium API Access') is undocumented and unknown.
- —No request parameters or response schema are available anywhere in the crawled content.
- —All documentation pages (/docs, /pricing, /api, /README) render only 'Connect wallet' with no useful content.
- —The platform lists many endpoints but none have detailed documentation visible without a connected wallet.
Citations
- —Endpoint returns 402 with x402 challenge, maxAmountRequired 20000 base units USDC on Basehttps://lowpaymentfee.com/api/v1/cards/78
- —Platform advertises $0.02 per request, no API keys, no rate limits, no minimumshttps://lowpaymentfee.com
- —USDC asset contract on Base is 0x833589fCD6eDb6E08f4c7C32D4f71b54bdA02913https://lowpaymentfee.com/api/v1/cards/78