x402-gated premium API endpoint on Base, pay-per-call with USDC at $0.02/request.
What it does
This endpoint at lowpaymentfee.com is part of a broader suite of x402-protocol pay-per-request APIs hosted on the Base network. The specific resource `/api/v1/cards/98` is listed under "Premium API Access" and accepts POST requests gated by an x402 payment challenge. Payment is settled in USDC (contract 0x833589fCD6eDb6E08f4c7C32D4f71b54bdA02913) on Base, with a maximum amount of 20,000 base units — equivalent to $0.02 per request (USDC uses 6 decimals). No API keys or rate limits are advertised; access is granted purely via the x402 payment header.
The provider's landing page advertises a wide catalog of endpoints spanning data & analytics, AI & machine learning (sentiment analysis, summarization, classification, embeddings), finance & Web3 (price feeds, exchange rates, token quotes, gas estimates), and infrastructure utilities (geocoding, validation, conversion, generation) — all at the same $0.02/request price point. However, the specific functionality behind `/api/v1/cards/98` is not documented beyond the label "Premium API Access." There is no OpenAPI schema, no request/response examples, and the docs, pricing, and API pages all render only a "Connect wallet" prompt with no additional content.
Because the endpoint's actual input parameters and response format are unknown, agents should treat this as a stub listing until the provider publishes documentation or an output schema. The x402 challenge is live and well-formed, confirming the endpoint is operational and ready to accept payments.
Capabilities
Use cases
- —Programmatic access to a premium API resource without traditional API key signup
- —Agent-driven pay-per-call workflows settled on-chain via USDC on Base
- —Exploring x402 protocol integrations for micropayment-gated services
Fit
Best for
- —Developers experimenting with x402 payment protocol
- —Agents that can settle USDC payments on Base L2
- —Use cases requiring keyless, pay-as-you-go API access
Not for
- —Users who need documented request/response schemas before integration
- —Applications requiring free or fiat-settled API access
- —Production workloads that depend on well-documented endpoint behavior
Quick start
# The endpoint returns 402 with an x402 challenge.
# After constructing a valid X-PAYMENT header (USDC on Base),
# POST to the resource:
curl -X POST https://lowpaymentfee.com/api/v1/cards/98 \
-H "X-PAYMENT: <signed-x402-payment-token>" \
-H "Content-Type: application/json"Endpoint
Quality
The x402 challenge is live and well-formed, confirming the endpoint is operational. However, there is no documentation, no OpenAPI schema, no request/response examples, and the specific functionality of /api/v1/cards/98 is entirely undescribed beyond a generic 'Premium API Access' label. Docs pages render only a wallet-connect prompt.
Warnings
- —The specific functionality of /api/v1/cards/98 is undocumented — the label 'Premium API Access' provides no detail on what data or service is returned.
- —No OpenAPI spec, request schema, or response schema is available.
- —All documentation pages (docs, pricing, API, README) render only a 'Connect wallet' prompt with no substantive content.
- —The broader site lists many endpoint categories (AI, finance, analytics, etc.) but none map clearly to the /cards/98 path.
Citations
- —The endpoint returns a 402 x402 challenge with maxAmountRequired of 20000 base units in USDC on Basehttps://lowpaymentfee.com/api/v1/cards/98
- —USDC asset contract is 0x833589fCD6eDb6E08f4c7C32D4f71b54bdA02913 on Base networkhttps://lowpaymentfee.com/api/v1/cards/98
- —All APIs priced at $0.02/request with no API keys, no rate limits, and instant access on Base networkhttps://lowpaymentfee.com
- —Docs, pricing, API, and README pages render only a 'Connect wallet' prompthttps://lowpaymentfee.com/docs