Pay-per-call API platform on Base (USDC) via x402 — $0.02/request, no API keys required.
What it does
lowpaymentfee.com is an x402-enabled API platform that offers a broad set of endpoints spanning data analytics, AI/ML inference, finance/Web3 data, and utility services. Every endpoint is priced at $0.02 per request, payable in USDC on the Base network. The x402 protocol means there are no API keys, no sign-up, and no rate limits — callers simply attach an X-PAYMENT header with a valid payment proof to each request.
The specific endpoint at `/api/v1/charges/99` is listed 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 platform advertises 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).
Documentation is extremely sparse — the /docs, /pricing, /api, 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 from the crawl. The endpoint is live and responds with a well-formed x402 challenge, but without documentation it is unclear what request body this particular endpoint expects or what it returns.
Capabilities
Use cases
- —Accessing AI inference (sentiment, summarization, classification, embeddings) without API key management
- —Fetching real-time crypto prices, gas estimates, and exchange rates on a per-call basis
- —Running geocoding or data validation utilities with instant pay-per-use billing
- —Exporting analytics data or generating insights reports via micropayments
Fit
Best for
- —Developers who want zero-signup, pay-as-you-go API access
- —Agents and bots that can settle payments in USDC on Base via x402
- —Projects needing low-cost utility and AI endpoints without rate limits
Not for
- —Users who need detailed API documentation or OpenAPI specs before integrating
- —Teams requiring traditional API key authentication or OAuth flows
- —High-volume consumers who need bulk pricing or subscription discounts
Quick start
# Send a POST with x402 payment header
curl -X POST https://lowpaymentfee.com/api/v1/charges/99 \
-H "Content-Type: application/json" \
-H "X-PAYMENT: <x402-payment-proof>" \
-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, and no examples. The specific purpose of /api/v1/charges/99 vs. the other listed endpoints is unclear.
Warnings
- —Documentation pages (/docs, /pricing, /api, /README) all render only 'Connect wallet' with no usable content
- —No OpenAPI or schema documentation available — request and response formats are unknown
- —The specific function of /api/v1/charges/99 ('Premium API Access') is not explained anywhere
- —No examples of successful responses are available
Citations
- —Endpoint returns 402 with x402 challenge requesting 20000 base units of USDC on Basehttps://lowpaymentfee.com/api/v1/charges/99
- —Platform lists endpoints across Data & Analytics, AI & ML, Finance & Web3, and Infrastructure categories all at $0.02/requesthttps://lowpaymentfee.com
- —Pricing is $0.02 per request with no API keys, no rate limits, and instant access on Base networkhttps://lowpaymentfee.com
- —USDC asset address 0x833589fCD6eDb6E08f4c7C32D4f71b54bdA02913 on Base networkhttps://lowpaymentfee.com/api/v1/charges/99