Pay-per-call API platform on Base network via x402 — $0.02/request in USDC.
What it does
lowpaymentfee.com is an x402-enabled API platform that offers a variety of endpoints across data analytics, AI/ML inference, finance/Web3, and infrastructure utilities. 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 commitments required. The x402 payment protocol allows agents and users to pay per call by attaching an X-PAYMENT header to each request.
The specific endpoint at `/api/v1/charges/44` is listed as "Premium API Access" and returns a 402 challenge requesting up to 20,000 base units of USDC (0x8335…2913 on Base). Since USDC uses 6 decimals, this equals $0.02 per request, consistent with the site's advertised pricing. The payment scheme is "exact" with a 300-second timeout, settling to address 0x1A2B13E97f5F837C8F9FA1F95a1484B7C70d85F3.
The broader platform advertises 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. However, documentation beyond the landing page is extremely sparse (docs, pricing, and README pages all render only a "Connect wallet" prompt), so the actual request/response schemas for these endpoints are unknown. The specific functionality behind the `/api/v1/charges/44` "Premium API Access" endpoint is not documented.
Capabilities
Use cases
- —Agents making ad-hoc API calls without needing pre-registered API keys
- —Paying per request for data, AI inference, or utility endpoints using USDC on Base
- —Integrating x402-compatible payment flows into automated workflows
Fit
Best for
- —Developers or agents wanting zero-commitment, pay-as-you-go API access
- —x402-native agents that can attach payment headers automatically
- —Use cases requiring low-cost per-call pricing without subscriptions
Not for
- —Users who need detailed API documentation or well-defined schemas before integrating
- —High-volume use cases where subscription pricing would be more cost-effective
- —Users without access to USDC on the Base network
Quick start
curl -X POST https://lowpaymentfee.com/api/v1/charges/44 \
-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 payment details. However, there is no documentation of what the endpoint actually does, no request/response schema, and no examples. The docs, pricing, and README pages are all empty beyond a wallet-connect prompt. The listing is effectively a stub with confirmed liveness.
Warnings
- —The specific functionality of /api/v1/charges/44 ('Premium API Access') is completely undocumented — it is unclear what data or service it provides.
- —All documentation pages (docs, pricing, README) render only 'Connect wallet' with no actual content.
- —No OpenAPI spec, request schema, or response schema is available for any endpoint.
- —The broader platform lists many endpoints (AI, finance, utils) but none have documented schemas or examples.
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 for /api/v1/charges/44 requests maxAmountRequired of 20000 base units of USDC (asset 0x833589fCD6eDb6E08f4c7C32D4f71b54bdA02913) on Basehttps://lowpaymentfee.com/api/v1/charges/44
- —Platform offers endpoints across Data & Analytics, AI & Machine Learning, Finance & Web3, and Infrastructure categorieshttps://lowpaymentfee.com