Pay-per-call API platform on Base via x402 — data, AI, finance, and utility endpoints at $0.02/request.
What it does
lowpaymentfee.com is an x402-enabled API platform that offers a broad catalog of pay-per-request 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.
The specific endpoint at `/api/v1/charges/42` is labeled "Premium API Access" and returns a valid x402 challenge requesting up to 20,000 base units of USDC (0.02 USD, since USDC uses 6 decimals) on Base. Payment is made via the x402 exact scheme with no API keys, no rate limits, and no upfront commitments required. The endpoint accepts POST requests and returns application/json.
Documentation is extremely sparse — the /docs, /api, /pricing, and /README pages all render only a "Connect wallet" prompt with no further content. There is no OpenAPI spec, no request/response schema documentation, and no usage examples available. The exact functionality behind the `/api/v1/charges/42` "Premium API Access" endpoint is unclear; it may be a generic charge endpoint or a specific resource. Without documentation, callers will need to experiment to determine the expected request body and response format.
Capabilities
Use cases
- —Accessing AI inference (sentiment, summarization, classification, embeddings) without API key signup
- —Fetching real-time crypto price feeds and gas estimates with per-call USDC payments
- —Running geocoding or data validation requests on a pay-as-you-go basis
- —Exporting analytics data or generating reports without subscription commitments
Fit
Best for
- —Developers who want instant API access without registration or API keys
- —Agents and bots that can settle x402 payments in USDC on Base
- —Low-volume or sporadic API consumers who prefer per-call pricing over subscriptions
Not for
- —High-volume production workloads needing guaranteed SLAs and detailed documentation
- —Users without a Base-compatible USDC wallet or x402 client
Quick start
curl -X POST https://lowpaymentfee.com/api/v1/charges/42 \
-H "Content-Type: application/json" \
-H "X-PAYMENT: <x402-payment-token>" \
-d '{}'Endpoint
Quality
The endpoint is live and returns a valid x402 402 challenge, confirming it works. However, documentation is essentially nonexistent — all doc pages show only 'Connect wallet'. There is no OpenAPI spec, no request/response schema, no examples, and the purpose of '/api/v1/charges/42' specifically is unclear. Pricing is clear ($0.02/request in USDC on Base).
Warnings
- —Documentation pages (/docs, /api, /pricing, /README) are all empty beyond a 'Connect wallet' prompt — no usable docs available.
- —No OpenAPI or schema definition found; request body and response format for this endpoint are unknown.
- —The specific purpose of /api/v1/charges/42 ('Premium API Access') is not explained anywhere — it may be a generic or placeholder endpoint.
- —The site lists many endpoints but none have detailed documentation; actual functionality is unverified.
Citations
- —The endpoint returns a valid x402 challenge with maxAmountRequired of 20000 base units of USDC on Basehttps://lowpaymentfee.com/api/v1/charges/42
- —All listed endpoints are priced at $0.02 per request with no API keys, no rate limits, and instant access on Base networkhttps://lowpaymentfee.com
- —The platform offers endpoints across Data & Analytics, AI & ML, Finance & Web3, and Infrastructure categorieshttps://lowpaymentfee.com
- —USDC asset address 0x833589fCD6eDb6E08f4c7C32D4f71b54bdA02913 on Base networkhttps://lowpaymentfee.com/api/v1/charges/42