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 micropayments settled in USDC on the Base network. The specific endpoint at `/api/v1/cards/94` is listed as "Premium API Access" and costs up to $0.02 per call (20,000 base units of USDC with 6 decimals). Payment is handled 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. The x402 challenge confirms the endpoint is live and accepts POST requests returning application/json.
Documentation is extremely sparse — the docs, API, pricing, and README pages all render only a "Connect wallet" prompt with no further technical detail. There is no OpenAPI spec, no request/response schema documentation, and no usage examples available from the crawled content. The exact functionality behind `/api/v1/cards/94` (labeled generically as "Premium API Access") is unclear and does not map obviously to any of the listed API categories.
Capabilities
Use cases
- —Accessing premium API endpoints without traditional API key management
- —Making one-off API calls with instant USDC micropayments on Base
- —Integrating pay-per-use data, AI, or finance APIs into agent workflows
Fit
Best for
- —Developers who want keyless, pay-per-call API access
- —AI agents that can settle x402 payments autonomously on Base
- —Projects needing low-friction access to miscellaneous utility APIs
Not for
- —Users who need detailed API documentation or OpenAPI specs before integrating
- —High-volume consumers who prefer subscription-based pricing over per-call fees
Quick start
# The endpoint returns 402 with an x402 challenge.
# After constructing a valid X-PAYMENT header (USDC on Base, up to $0.02):
curl -X POST https://lowpaymentfee.com/api/v1/cards/94 \
-H 'X-PAYMENT: <signed-x402-payment-token>' \
-H 'Content-Type: application/json'Endpoint
Quality
The x402 challenge is live and confirms pricing and payment details, but there is zero documentation on what this specific endpoint does, no request/response schemas, and no examples. The endpoint path '/api/v1/cards/94' does not correspond to any documented API category. This is effectively a stub listing.
Warnings
- —No OpenAPI spec or schema available for request or response
- —Documentation pages (docs, API, pricing, README) all render only 'Connect wallet' with no content
- —The endpoint path /api/v1/cards/94 is not listed among the site's advertised APIs — its actual functionality is unknown
- —No request body schema or response examples could be determined
Citations
- —The endpoint returns a 402 x402 challenge with maxAmountRequired of 20000 base units of USDC on Basehttps://lowpaymentfee.com/api/v1/cards/94
- —All listed APIs are priced at $0.02/request with no API keys, no rate limits, and instant access on Base networkhttps://lowpaymentfee.com
- —The platform offers Data & Analytics, AI & ML, Finance & Web3, and Infrastructure API categorieshttps://lowpaymentfee.com
- —USDC asset contract on Base is 0x833589fCD6eDb6E08f4c7C32D4f71b54bdA02913https://lowpaymentfee.com/api/v1/cards/94