x402-gated premium API endpoint on Base, pay $0.02 per request in USDC.
What it does
This endpoint at `/api/v1/cards/85` 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/85` is labeled "Premium API Access" but its exact functionality is not documented beyond that label. All endpoints on the platform share the same pricing model: $0.02 per request, settled in USDC on the Base network.
The x402 challenge confirms the endpoint is live and accepts POST requests. Payment is made via the x402 exact scheme, requiring up to 20,000 base units of USDC (0x8335…2913 on Base), which equals $0.02 given USDC's 6 decimals. There are no API keys, no rate limits, and no signup required — callers simply attach an X-PAYMENT header with a valid x402 payment proof. The payment recipient address is 0x1A2B13E97f5F837C8F9FA1F95a1484B7C70d85F3, and the maximum timeout for payment settlement is 300 seconds.
Documentation is extremely sparse. The docs, pricing, API, and README pages all render only a "Connect wallet" prompt with no additional content. There is no OpenAPI spec, no request/response schema, and no description of what `/api/v1/cards/85` actually returns. The platform lists many other endpoints (analytics, AI, finance, utilities) but provides no detail on any of them beyond names and prices. Without knowing what "cards/85" delivers, agents should treat this as an opaque premium endpoint with uncertain output.
Capabilities
Use cases
- —Accessing a premium data resource without signup or API keys
- —Programmatic pay-per-request access from AI agents on Base
- —Testing x402 payment flows against a live endpoint
Fit
Best for
- —Agents that need keyless, pay-per-call API access on Base
- —Developers experimenting with x402 protocol integrations
- —Scenarios requiring no rate limits and instant access
Not for
- —Users who need documented request/response schemas before calling
- —High-volume use cases where $0.02/request adds up without clear value
- —Anyone needing to understand exactly what the endpoint returns before paying
Quick start
curl -X POST https://lowpaymentfee.com/api/v1/cards/85 \
-H "Content-Type: application/json" \
-H "X-PAYMENT: <x402-payment-proof>"Endpoint
Quality
The endpoint is live (402 challenge confirmed) and pricing is clear ($0.02 USDC on Base), but there is no documentation, no OpenAPI spec, no request/response schema, and no explanation of what '/api/v1/cards/85' actually returns. This is effectively a stub listing.
Warnings
- —No documentation available — docs, pricing, API, and README pages all show only 'Connect wallet' with no content.
- —The purpose and output of /api/v1/cards/85 ('Premium API Access') is completely undocumented; callers cannot know what they are paying for.
- —No OpenAPI spec or request/response schema is provided.
- —No examples of successful responses are available.
Citations
- —The endpoint returns a 402 x402 challenge with maxAmountRequired of 20000 base units of USDC on Basehttps://lowpaymentfee.com/api/v1/cards/85
- —All endpoints on the platform cost $0.02 per request with no API keys, no rate limits, and instant access on Base networkhttps://lowpaymentfee.com
- —USDC asset contract on Base is 0x833589fCD6eDb6E08f4c7C32D4f71b54bdA02913https://lowpaymentfee.com/api/v1/cards/85
- —Docs, pricing, API, and README pages render only 'Connect wallet' with no additional contenthttps://lowpaymentfee.com/docs