Pay-per-call API platform on Base offering data, AI, finance, and utility endpoints at $0.02 each via x402.
What it does
lowpaymentfee.com is an x402-enabled API platform that exposes a broad set of endpoints across four categories: 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, paid in USDC on the Base network with no API keys, no rate limits, and no minimum commitments.
The specific endpoint being listed here — `/api/v1/transactions/9/receipt` — is described as "Premium API Access" and returns a 402 challenge requesting up to 20,000 base units of USDC (0.02 USDC, i.e., $0.02) on Base. The x402 challenge confirms the endpoint is live, accepts POST requests, and returns `application/json`. The payment is settled on-chain to address `0x1A2B13E97f5F837C8F9FA1F95a1484B7C70d85F3` using the USDC contract at `0x833589fCD6eDb6E08f4c7C32D4f71b54bdA02913`.
Documentation beyond the landing page is extremely sparse — the /docs, /api, /pricing, and /README pages all render only a "Connect wallet" prompt with no additional technical content. There is no OpenAPI spec, no request/response schema documentation, and no examples of what this particular receipt endpoint actually returns. The endpoint path suggests it retrieves a receipt for transaction ID 9, but the exact payload structure is unknown.
Capabilities
Use cases
- —Retrieving transaction receipts via a pay-per-call model without API key registration
- —Integrating on-chain micropayment-gated endpoints into agent workflows
- —Accessing low-cost utility and data APIs settled in USDC on Base
Fit
Best for
- —Developers wanting zero-signup, pay-as-you-go API access
- —AI agents that can settle x402 payments autonomously on Base
- —Projects needing cheap per-call pricing without rate limits
Not for
- —Users who need detailed API documentation or OpenAPI specs before integrating
- —High-volume consumers who would benefit from bulk/subscription pricing
- —Anyone without a Base-compatible USDC wallet
Quick start
curl -X POST https://lowpaymentfee.com/api/v1/transactions/9/receipt \
-H "Content-Type: application/json" \
-H "X-PAYMENT: <x402-payment-token>"Endpoint
Quality
The endpoint is live and returns a valid x402 402 challenge, confirming pricing and network. However, there is no OpenAPI spec, no documentation of request/response schemas, no examples, and the docs pages are empty. The specific purpose of this 'transactions/9/receipt' endpoint is unclear beyond its name.
Warnings
- —No OpenAPI or schema documentation available — all docs pages render only 'Connect wallet'
- —The exact request body and response structure for this endpoint are undocumented
- —The endpoint path references a hardcoded transaction ID (9), which may indicate a demo or placeholder rather than a general-purpose API
- —No information on what 'Premium API Access' actually provides beyond the generic label
Citations
- —All endpoints priced at $0.02 per request with no API keys, no rate limits, and instant access on Base networkhttps://lowpaymentfee.com
- —The x402 challenge requests maxAmountRequired of 20000 base units of USDC (0.02 USD) on Basehttps://lowpaymentfee.com/api/v1/transactions/9/receipt
- —USDC asset contract is 0x833589fCD6eDb6E08f4c7C32D4f71b54bdA02913 on Basehttps://lowpaymentfee.com/api/v1/transactions/9/receipt
- —Available API categories include Data & Analytics, AI & Machine Learning, Finance & Web3, and Infrastructurehttps://lowpaymentfee.com