Pay-per-request API platform on Base network via x402 — $0.02/call in USDC.
What it does
lowpaymentfee.com is a pay-per-request API platform that uses the x402 protocol to accept USDC payments on the Base network. The specific endpoint `/api/v1/carts/51` is listed as "Premium API Access" and accepts POST requests with payment via the x402 exact scheme. The maximum amount required per call is 20,000 base units of USDC (0x8335…2913 on Base), which equals $0.02 given USDC's 6 decimals.
The broader platform advertises multiple API categories including 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 priced at $0.02 per request with no API keys, no rate limits, and no minimum commitments.
However, the specific endpoint being listed here (`/api/v1/carts/51`) is labeled only as "Premium API Access" with no further documentation about what data or functionality it returns. The docs, pricing, and README pages all returned only a "Connect wallet" prompt with no substantive content. Without an OpenAPI schema, example responses, or detailed documentation, the actual behavior of this particular endpoint remains unclear.
Capabilities
Use cases
- —Programmatic access to a premium API endpoint with per-request USDC micropayments
- —Agent-driven workflows that need keyless, pay-as-you-go API access on Base
- —Testing x402 protocol integrations with a low-cost endpoint
Fit
Best for
- —Developers experimenting with x402 payment protocol
- —Agents that need keyless API access settled in USDC on Base
- —Low-cost per-request API consumption without subscriptions
Not for
- —Users who need detailed API documentation or guaranteed SLAs
- —Applications requiring high-throughput with predictable flat-rate pricing
- —Anyone without a Base-compatible USDC wallet
Quick start
curl -X POST https://lowpaymentfee.com/api/v1/carts/51 \
-H "Content-Type: application/json" \
-H "X-PAYMENT: <x402-payment-token>"Endpoint
Quality
The endpoint is live (returns 402 with a valid x402 challenge), and pricing is clear ($0.02 USDC on Base). However, there is no OpenAPI schema, no example request/response, and no documentation beyond a generic label. The docs/pricing/README pages are all empty (just 'Connect wallet'). The specific functionality of /api/v1/carts/51 is entirely undocumented.
Warnings
- —No documentation available — docs, pricing, and README pages all return only 'Connect wallet'
- —The specific endpoint /api/v1/carts/51 ('Premium API Access') has no description of what it actually returns
- —No OpenAPI schema or example responses provided
- —No information about uptime, SLAs, or rate limits beyond the marketing claim of 'no rate limits'
Citations
- —The endpoint returns a 402 x402 challenge with maxAmountRequired of 20000 base units of USDC on Basehttps://lowpaymentfee.com/api/v1/carts/51
- —All endpoints priced at $0.02 per request with no API keys, no rate limits, and instant access on Base networkhttps://lowpaymentfee.com
- —Platform offers APIs across Data & Analytics, AI & ML, Finance & Web3, and Infrastructure categorieshttps://lowpaymentfee.com
- —USDC asset contract on Base is 0x833589fCD6eDb6E08f4c7C32D4f71b54bdA02913https://lowpaymentfee.com/api/v1/carts/51