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/19` 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. However, the specific endpoint `/api/v1/cards/19` does not clearly map to any of these named services — it may be a generic card-based resource or an internal identifier. No OpenAPI schema, detailed documentation, or example request/response payloads are available from the crawled pages (docs, pricing, and README pages all returned only a "Connect wallet" prompt with no substantive content).
Capabilities
Use cases
- —Accessing AI inference endpoints (sentiment, summarization, classification, embeddings) without API key management
- —Fetching real-time financial data like token quotes, gas estimates, and exchange rates on a pay-per-call basis
- —Running data analytics queries and exporting reports with no subscription commitment
- —Using utility services like geocoding, validation, and format conversion via micropayments
Fit
Best for
- —Agents or developers who want zero-signup, pay-as-you-go API access
- —Use cases requiring low-cost per-request billing without rate limits
- —Projects already operating on the Base network with USDC liquidity
Not for
- —Users who need detailed API documentation or OpenAPI schemas before integrating
- —High-volume consumers who would benefit from bulk pricing or subscription discounts
- —Developers without access to USDC on the Base network
Quick start
curl -X POST https://lowpaymentfee.com/api/v1/cards/19 \
-H "Content-Type: application/json" \
-H "X-PAYMENT: <x402-payment-token>"Endpoint
Quality
The endpoint is live (402 challenge confirmed) and pricing is clear ($0.02 USDC on Base), but there is no OpenAPI schema, no documentation beyond a landing page listing, no example request/response payloads, and the specific resource at /api/v1/cards/19 is not described. The docs, pricing, and README pages are effectively empty.
Warnings
- —No OpenAPI or schema documentation available — all doc pages return only 'Connect wallet' with no content
- —The endpoint path /api/v1/cards/19 does not correspond to any named API on the landing page; its actual functionality is unknown
- —No example request or response payloads are available to verify what this endpoint returns
- —Cannot confirm what data or service 'Premium API Access' actually provides
Citations
- —The endpoint returns a 402 x402 challenge with maxAmountRequired of 20000 base units of USDC on Basehttps://lowpaymentfee.com/api/v1/cards/19
- —All listed APIs are priced at $0.02 per request with no API keys, no rate limits, and instant access on the Base networkhttps://lowpaymentfee.com
- —The platform offers Data & Analytics, AI & ML, Finance & Web3, and Infrastructure utility API categorieshttps://lowpaymentfee.com
- —USDC asset address 0x833589fCD6eDb6E08f4c7C32D4f71b54bdA02913 on Base networkhttps://lowpaymentfee.com/api/v1/cards/19