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/carts/32` is listed as "Premium API Access" and requires a payment of up to 20,000 base units of USDC (i.e., $0.02 given USDC's 6 decimals) per call. Payment is made via the x402 exact scheme with no API keys, no rate limits, and no subscriptions required.
The broader platform advertises four categories of endpoints: 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 platform accepts POST requests and returns JSON responses.
Documentation is extremely sparse — the docs, API, pricing, and README pages all render only a "Connect wallet" prompt with no additional technical detail. There is no OpenAPI spec, no request/response schema documentation, and no usage examples available from the crawled content. The `/api/v1/carts/32` endpoint itself is confirmed live via a valid 402 challenge, but the actual behavior and response format of this specific cart endpoint (as opposed to the other listed API categories) is unclear.
Capabilities
Use cases
- —Paying per-call for data analytics or AI inference without managing API keys or subscriptions
- —Integrating agent-purchasable endpoints into autonomous workflows using x402 micropayments
- —Accessing utility services like geocoding or data conversion with instant crypto-settled billing
Fit
Best for
- —Developers or agents wanting zero-friction, keyless API access via crypto micropayments
- —x402-compatible agent wallets that can settle USDC on Base
- —Low-volume or bursty workloads where pay-per-request is more economical than subscriptions
Not for
- —Users who need detailed API documentation or OpenAPI specs before integrating
- —High-volume production workloads requiring SLAs, rate-limit guarantees, or support contracts
- —Users without a Base-compatible USDC wallet
Quick start
curl -X POST https://lowpaymentfee.com/api/v1/carts/32 \
-H "Content-Type: application/json" \
-H "X-PAYMENT: <x402-payment-header>"Endpoint
Quality
The endpoint is confirmed live via a valid x402 402 challenge, and pricing is clear ($0.02/request in USDC on Base). However, there is no OpenAPI spec, no request/response schema, no documentation beyond a wallet-connect prompt, and no examples. The specific purpose of the `/api/v1/carts/32` endpoint is unclear beyond the generic 'Premium API Access' label. This is effectively a stub listing.
Warnings
- —No OpenAPI spec or schema documentation available
- —Docs, API, pricing, and README pages all render only 'Connect wallet' with no technical content
- —The specific purpose and expected input/output of /api/v1/carts/32 is undocumented — it does not clearly map to any of the advertised API categories
- —No request or response examples could be obtained
Citations
- —The endpoint returns a valid x402 402 challenge with maxAmountRequired of 20000 base units of USDC on Basehttps://lowpaymentfee.com/api/v1/carts/32
- —USDC asset contract on Base is 0x833589fCD6eDb6E08f4c7C32D4f71b54bdA02913https://lowpaymentfee.com/api/v1/carts/32
- —All listed endpoints are priced at $0.02/request with no API keys, no rate limits, and instant access on Basehttps://lowpaymentfee.com
- —Platform offers endpoints in Data & Analytics, AI & ML, Finance & Web3, and Infrastructure categorieshttps://lowpaymentfee.com