x402-gated API marketplace on Base with $0.02/request USDC pricing and no API keys required.
What it does
lowpaymentfee.com is a pay-per-request API platform that uses the x402 protocol to gate access to a variety of endpoints spanning data analytics, AI/ML inference, finance/Web3 data, and utility services. Each call costs $0.02 in USDC on the Base network, settled on-chain to the provider's wallet. No API keys, accounts, or rate limits are advertised — callers simply attach an X-PAYMENT header with a valid x402 payment proof.
The specific endpoint at `/api/v1/carts/59` is listed as "Premium API Access" and accepts POST requests. Its x402 challenge advertises a maximum amount of 20,000 units of USDC (0x8335… on Base), which at 6 decimals equals $0.02. The response MIME type is application/json. However, the exact functionality of this particular cart endpoint is not documented in the crawled material — the site lists categories like analytics, AI, finance, and utilities, but `/api/v1/carts/59` does not appear among them.
The broader platform offers endpoints for 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 price point. Documentation pages (docs, pricing, README) returned only a "Connect wallet" prompt with no substantive content, so detailed request/response schemas are unavailable.
Capabilities
Use cases
- —Programmatic access to paid API endpoints without managing API keys or subscriptions
- —Agent-driven workflows that need on-demand, per-call billing via x402
- —Accessing a bundled set of analytics, AI, finance, and utility services through a single payment protocol
Fit
Best for
- —Developers or agents wanting frictionless pay-per-use API access on Base
- —x402-compatible clients that can attach USDC payment proofs automatically
- —Low-volume or exploratory usage where $0.02/call with no commitment is attractive
Not for
- —High-volume production workloads where per-call crypto payments add latency and cost overhead
- —Users who need detailed API documentation, SLAs, or guaranteed uptime
- —Anyone without a Base-compatible wallet or x402 client
Quick start
curl -X POST https://lowpaymentfee.com/api/v1/carts/59 \
-H "Content-Type: application/json" \
-H "X-PAYMENT: <x402_payment_proof>"Endpoint
Quality
The endpoint is live (402 challenge captured) and pricing is clear ($0.02 USDC on Base), but the specific /api/v1/carts/59 endpoint has no documentation, no input/output schema, and no examples. All doc pages returned only 'Connect wallet' with no content. The purpose of this particular cart endpoint is unknown.
Warnings
- —The /api/v1/carts/59 endpoint is not listed among the site's advertised APIs — its specific function is unclear.
- —All documentation pages (/docs, /pricing, /README, /api) returned no substantive content, only 'Connect wallet'.
- —No input or output schema is available; callers cannot know what to send or what to expect back.
- —The platform's actual service delivery behind these endpoints is unverifiable from the crawl data.
Citations
- —The site advertises $0.02/request pricing with no API keys, no rate limits, and instant access on Base network.https://lowpaymentfee.com
- —The x402 challenge for /api/v1/carts/59 specifies maxAmountRequired of 20000 units of USDC (asset 0x833589fCD6eDb6E08f4c7C32D4f71b54bdA02913) on Base.https://lowpaymentfee.com/api/v1/carts/59
- —Available API categories include Data & Analytics, AI & Machine Learning, Finance & Web3, and Infrastructure.https://lowpaymentfee.com
- —Documentation pages returned only 'Connect wallet' with no substantive content.https://lowpaymentfee.com/docs