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 a variety of endpoints behind per-request micropayments settled in USDC on the Base network. The specific endpoint `/api/v1/cards/38` is listed as "Premium API Access" and costs up to $0.02 per call (maxAmountRequired of 20,000 base units of USDC, which has 6 decimals = $0.02). Payment is handled via the x402 exact scheme — no API keys, no rate limits, and no sign-up 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 `/api/v1/cards/38` endpoint itself lacks detailed documentation — the docs, pricing, and README pages all render only a "Connect wallet" prompt with no further content. There is no OpenAPI spec, no request/response schema documentation, and no usage examples available from the crawled material. The endpoint is confirmed live (returns a proper 402 x402 challenge), but what data or functionality "Premium API Access" specifically provides at this path is unclear from the available information.
Capabilities
Use cases
- —Agents that need on-demand API access without pre-registration or API key management
- —Paying per-call for data, AI inference, or utility endpoints using USDC on Base
- —Integrating x402-compatible payment flows into automated workflows
Fit
Best for
- —Developers or agents wanting zero-signup, pay-as-you-go API access
- —x402-native agents that can settle USDC micropayments on Base
- —Low-volume or bursty workloads where per-request pricing is preferable to subscriptions
Not for
- —High-volume production workloads where $0.02/request adds up significantly
- —Users who need detailed API documentation or guaranteed SLAs before integrating
- —Anyone without a Base-compatible USDC wallet
Quick start
# The endpoint requires an x402 payment header (USDC on Base).
# 1. Send POST to get the 402 challenge:
curl -X POST https://lowpaymentfee.com/api/v1/cards/38
# 2. Parse the 402 response, construct an X-PAYMENT header
# with a signed USDC transfer of 20000 base units ($0.02),
# then resend the request with that header.Endpoint
Quality
The endpoint is confirmed live with a valid x402 402 challenge, but there is no OpenAPI spec, no request/response schema, no documentation beyond a wallet-connect prompt, and the specific functionality of '/api/v1/cards/38' is undocumented. The listing is effectively a stub with only pricing and protocol details available.
Warnings
- —No OpenAPI or schema documentation available for this endpoint
- —The docs, pricing, and README pages render only 'Connect wallet' with no usable content
- —The specific functionality of /api/v1/cards/38 ('Premium API Access') is not described anywhere in the crawled material
- —Cannot determine what request body to send or what response to expect
Citations
- —Endpoint returns a valid x402 402 challenge with maxAmountRequired of 20000 USDC base units on Basehttps://lowpaymentfee.com/api/v1/cards/38
- —USDC asset address 0x833589fCD6eDb6E08f4c7C32D4f71b54bdA02913 on Base networkhttps://lowpaymentfee.com/api/v1/cards/38
- —All listed endpoints priced at $0.02/request with no API keys, no rate limits, instant access on Base networkhttps://lowpaymentfee.com
- —Platform offers Data & Analytics, AI & ML, Finance & Web3, and Infrastructure API categorieshttps://lowpaymentfee.com