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/82` is listed as "Premium API Access" and requires a maximum payment of 20,000 base units of USDC (0.02 USD, since USDC uses 6 decimals) per call via the x402 exact payment scheme.
The 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 $0.02 per request with no API keys, no rate limits, and no minimum commitments required.
The specific endpoint `/api/v1/carts/82` does not have a clear description beyond "Premium API Access," and the crawled documentation pages (docs, api, pricing, README) all returned only a "Connect wallet" prompt with no substantive content. There is no OpenAPI schema, no request/response examples, and no detailed documentation available. The endpoint is confirmed live via a valid 402 challenge response, but what it actually returns upon successful payment is unknown.
Capabilities
Use cases
- —Accessing premium API data with per-call USDC micropayments on Base
- —Agent-driven API consumption without pre-registration or API keys
- —Pay-as-you-go access to data, AI, finance, or utility endpoints
Fit
Best for
- —Developers wanting zero-commitment, pay-per-use API access
- —AI agents that can settle x402 payments autonomously on Base
- —Users who prefer crypto micropayments over subscription billing
Not for
- —Users needing detailed API documentation or OpenAPI specs before purchasing
- —High-volume consumers who need bulk pricing or rate guarantees
- —Anyone without a Base-compatible USDC wallet
Quick start
# The endpoint requires an x402 payment header (USDC on Base).
# 1. POST to the endpoint without payment to get the 402 challenge:
curl -X POST https://lowpaymentfee.com/api/v1/carts/82
# 2. Parse the 402 response, construct an X-PAYMENT header with
# a signed USDC transfer of 0.02 USD to 0x1A2B...85F3,
# then retry with the header attached.Endpoint
Quality
The endpoint is confirmed live via a valid x402 402 challenge, and pricing is clear ($0.02 USDC on Base). However, there is no OpenAPI schema, no documentation beyond a wallet-connect prompt, no request/response examples, and the actual functionality behind '/api/v1/carts/82' is entirely opaque. The listing is effectively a stub.
Warnings
- —No OpenAPI schema or detailed documentation available — all doc pages return only 'Connect wallet'
- —The specific functionality of /api/v1/carts/82 ('Premium API Access') is not described anywhere
- —No request body schema or response schema is documented
- —Cannot verify what data or service is actually delivered upon successful payment
Citations
- —The endpoint returns a 402 challenge requiring 20,000 base units of USDC (asset 0x833589fCD6eDb6E08f4c7C32D4f71b54bdA02913) on Base networkhttps://lowpaymentfee.com/api/v1/carts/82
- —All listed APIs are priced at $0.02 per request with no API keys, no rate limits, and instant access on Base networkhttps://lowpaymentfee.com
- —The platform offers APIs across Data & Analytics, AI & Machine Learning, Finance & Web3, and Infrastructure categorieshttps://lowpaymentfee.com