x402-gated API platform on Base offering data, AI, finance, and utility endpoints at $0.02/request.
What it does
lowpaymentfee.com is an x402-protocol API marketplace that gates access to a variety of endpoints behind per-request USDC micropayments on the Base network. The specific endpoint `/api/v1/cards/91` is listed as "Premium API Access" and costs $0.02 per call (20,000 base units of USDC with 6 decimals). Payment is made via the x402 exact scheme — no API keys, no rate limits, and no subscriptions required.
The broader platform advertises four categories of APIs: Data & Analytics (metrics, reports, data export, insights), 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 endpoints are listed at the same $0.02/request price point and settle in USDC on Base.
Note that the specific functionality behind `/api/v1/cards/91` is not documented beyond the label "Premium API Access." The docs, pricing, and API pages all render only a "Connect wallet" prompt with no further technical documentation, OpenAPI schema, or example payloads. Without additional documentation it is unclear what request body this endpoint expects or what response it returns. Agents should treat this as a low-documentation endpoint and test with caution.
Capabilities
Use cases
- —Accessing gated API endpoints without traditional API key registration
- —Making one-off paid API calls settled in USDC on Base
- —Agent-driven programmatic access to paid data or utility services
Fit
Best for
- —Developers who want keyless, pay-per-call API access
- —AI agents with x402-compatible wallets on Base
- —Users who prefer crypto micropayments over subscription billing
Not for
- —Users who need detailed API documentation or OpenAPI specs before integrating
- —High-volume consumers who would benefit from bulk pricing or subscriptions
- —Users without a Base-compatible USDC wallet
Quick start
# Send a POST with x402 payment header to access the endpoint
curl -X POST https://lowpaymentfee.com/api/v1/cards/91 \
-H "Content-Type: application/json" \
-H "X-PAYMENT: <x402-payment-token>"Endpoint
Quality
The endpoint is live (returns 402 with a valid x402 challenge) and pricing is clear ($0.02 USDC on Base). However, there is no OpenAPI schema, no request/response examples, and the docs pages are empty beyond a wallet-connect prompt. The specific purpose of /api/v1/cards/91 is undocumented.
Warnings
- —No API documentation available — docs, pricing, and API pages only show 'Connect wallet'
- —The specific functionality of /api/v1/cards/91 ('Premium API Access') is not described anywhere
- —No OpenAPI spec, no request body schema, and no example responses are provided
- —Cannot verify what data or service this endpoint actually returns
Citations
- —The endpoint returns a 402 x402 challenge with maxAmountRequired of 20000 in USDC (asset 0x8335…) on Base networkhttps://lowpaymentfee.com/api/v1/cards/91
- —All listed APIs cost $0.02 per request with no API keys, no rate limits, and instant access on Base networkhttps://lowpaymentfee.com
- —The platform offers APIs in Data & Analytics, AI & Machine Learning, Finance & Web3, and Infrastructure categorieshttps://lowpaymentfee.com