x402-gated API marketplace on Base: analytics, AI, finance, and utility endpoints at $0.02/request.
What it does
lowpaymentfee.com is an x402-enabled API marketplace that offers a collection of endpoints spanning data analytics, AI/ML inference, finance/Web3 data, and general utility services. All endpoints are pay-per-request using USDC on the Base network, with no API keys, no rate limits, and no minimum commitments required.
The specific endpoint at `/api/v1/carts/31` is listed as "Premium API Access" and accepts POST requests. Its x402 challenge advertises a maximum cost of 20,000 base units of USDC (0x8335…2913 on Base), which equals $0.02 per request (USDC uses 6 decimals). Payment is made via the x402 exact scheme, settling to address 0x1A2B13E97f5F837C8F9FA1F95a1484B7C70d85F3 with a 300-second timeout.
The broader platform advertises additional endpoints including sentiment analysis, text summarization, classification, embeddings, price feeds, exchange rates, token quotes, gas estimates, geocoding, validation, conversion, and generation — all at the same $0.02/request price point. However, documentation pages (/docs, /pricing, /api, /README) returned only a "Connect wallet" prompt with no substantive content, so the actual behavior and response schemas of these endpoints remain undocumented and unverified.
Capabilities
Use cases
- —Agents needing on-demand AI inference (sentiment, summarization, classification, embeddings) without API key management
- —Fetching real-time crypto token quotes and gas estimates via micropayment
- —Geocoding and data validation as lightweight utility calls
- —Exporting analytics data or generating reports on a per-request basis
Fit
Best for
- —AI agents that need keyless, pay-per-call access to diverse API endpoints
- —Developers prototyping with low-cost, no-commitment API access
- —Web3-native applications already operating on Base with USDC
Not for
- —High-volume production workloads where $0.02/request adds up significantly
- —Users who need detailed API documentation, SLAs, or guaranteed uptime
- —Applications requiring non-crypto payment methods
Quick start
curl -X POST https://lowpaymentfee.com/api/v1/carts/31 \
-H "Content-Type: application/json" \
-H "X-PAYMENT: <x402-payment-token>"Endpoint
Quality
The endpoint is live (402 challenge captured) and pricing is clear ($0.02 USDC on Base). However, there is no OpenAPI schema, no documentation of request/response formats, and all doc pages return only 'Connect wallet' with no content. The purpose of the specific /carts/31 endpoint is unclear beyond the generic 'Premium API Access' label. Effectively a stub listing.
Warnings
- —No API documentation available — /docs, /pricing, /api, and /README all return only 'Connect wallet' with no substantive content
- —The specific endpoint /api/v1/carts/31 has no documented request or response schema; its actual functionality is unknown
- —No OpenAPI spec or ai-plugin manifest found
- —The relationship between /api/v1/carts/31 and the other advertised endpoints (analytics, AI, finance, utils) is unclear
Citations
- —All endpoints priced at $0.02/request with no API keys, no rate limits, and instant access on Base networkhttps://lowpaymentfee.com
- —x402 challenge returns maxAmountRequired of 20000 base units of USDC (0x833589fCD6eDb6E08f4c7C32D4f71b54bdA02913) on Base, equaling $0.02https://lowpaymentfee.com/api/v1/carts/31
- —Platform offers endpoints across Data & Analytics, AI & Machine Learning, Finance & Web3, and Infrastructure categorieshttps://lowpaymentfee.com