Pay-per-call premium API access on Base via x402 — $0.02/request in USDC.
What it does
This endpoint at lowpaymentfee.com provides "Premium API Access" via the x402 payment protocol. The probed endpoint (/api/v1/payments/254) is live and returns a 402 challenge requesting payment in USDC on the Base network. The site advertises a broad catalog of API endpoints spanning data & analytics, AI & machine learning, finance & Web3, and infrastructure utilities — all priced at $0.02 per request.
The x402 challenge for this specific endpoint shows a maxAmountRequired of 20000 base units of USDC (0x833589fCD6eDb6E08f4c7C32D4f71b54bdA02913 on Base, 6 decimals), which equals $0.02. Payment is made via the x402 exact scheme with no API keys, no rate limits, and no upfront commitments required. The payment address is 0x1A2B13E97f5F837C8F9FA1F95a1484B7C70d85F3 with a 300-second timeout.
However, the specific functionality behind this particular endpoint (/api/v1/payments/254) is unclear — the description is simply "Premium API Access" with no further documentation on what data or service it returns. The docs, pricing, and API pages on the site all render only a "Connect wallet" prompt with no additional content. There is no OpenAPI spec, no request/response schema documentation, and no examples available. The site lists many other endpoints (sentiment analysis, summarization, geocoding, etc.) but none of them were probed, and it is unknown whether /api/v1/payments/254 maps to one of those or is a separate resource.
Capabilities
Use cases
- —Accessing paid API endpoints without API key registration
- —Making one-off API calls with per-request USDC micropayments on Base
- —Agent-driven programmatic access to paid services via x402 protocol
Fit
Best for
- —Developers wanting zero-signup pay-per-use API access
- —AI agents that can settle x402 payments autonomously
- —Users already holding USDC on Base who want frictionless API calls
Not for
- —Users needing detailed API documentation or schemas before purchasing
- —Anyone without USDC on the Base network
- —High-volume use cases where per-request payment overhead is undesirable
Quick start
# 1. Send a POST to discover the x402 payment challenge:
curl -X POST https://lowpaymentfee.com/api/v1/payments/254
# Returns 402 with x402 challenge header.
# 2. Construct and attach X-PAYMENT header with signed USDC payment on Base.
# 3. Re-send the POST with the payment header to receive the response.Endpoint
Quality
The endpoint is live and returns a valid x402 challenge, confirming pricing and payment details. However, there is no documentation on what the endpoint actually does, no OpenAPI spec, no request/response schemas, and no examples. The docs pages are empty (wallet-connect only). The specific purpose of /api/v1/payments/254 is unknown.
Warnings
- —No documentation available — docs, pricing, and API pages only show 'Connect wallet'
- —No OpenAPI or schema describing request parameters or response format
- —The specific functionality of /api/v1/payments/254 is undocumented and unclear
- —No example requests or responses available anywhere in crawled content
- —The site lists many endpoints but it is unknown if this endpoint maps to any of them
Citations
- —The endpoint returns a 402 challenge with maxAmountRequired of 20000 base units of USDC on Basehttps://lowpaymentfee.com/api/v1/payments/254
- —All listed APIs are priced at $0.02 per request with no API keys, no rate limits, and instant accesshttps://lowpaymentfee.com
- —The site offers endpoints across Data & Analytics, AI & ML, Finance & Web3, and Infrastructure categorieshttps://lowpaymentfee.com
- —USDC contract on Base is 0x833589fCD6eDb6E08f4c7C32D4f71b54bdA02913https://lowpaymentfee.com/api/v1/payments/254