Pay-per-call API platform on Base (USDC) offering data, AI, finance, and utility endpoints at $0.02/request.
What it does
lowpaymentfee.com is an x402-enabled API platform that hosts a broad collection of endpoints spanning data & analytics, AI & machine learning, finance & Web3, and infrastructure utilities. Every endpoint is priced at $0.02 per request, settled in USDC on the Base network via the x402 payment protocol. There are no API keys, no rate limits, and no minimum commitments — callers simply attach an X-PAYMENT header with a valid payment proof to each request.
The specific endpoint at `/api/v1/inbox/193` is listed as "Premium API Access" and accepts POST requests. Its x402 challenge advertises a maxAmountRequired of 20,000 base units of USDC (0x8335…2913 on Base), which equals $0.02 given USDC's 6 decimals. The response MIME type is application/json. The broader platform also exposes 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.
Documentation beyond the landing page is sparse: the /api, /pricing, and /README routes all resolve to a "Connect wallet" prompt with no further content. There is no OpenAPI spec, no detailed input/output schema, and no usage examples available from the crawl. The endpoint is confirmed live (returns HTTP 402 with a well-formed x402 challenge).
Capabilities
Use cases
- —Agent-driven data retrieval without managing API keys or subscriptions
- —On-demand AI inference (sentiment, summarization, classification, embeddings) paid per call
- —Fetching real-time crypto token quotes and gas estimates
- —Geocoding and data validation as utility microservices
Fit
Best for
- —AI agents that need frictionless, key-less API access with crypto micropayments
- —Developers prototyping integrations who want zero-commitment pay-as-you-go pricing
- —Web3-native applications already operating on the Base network
Not for
- —High-volume production workloads that need bulk pricing or SLAs
- —Users who require detailed API documentation, SDKs, or OpenAPI specs before integrating
Quick start
curl -X POST https://lowpaymentfee.com/api/v1/inbox/193 \
-H "Content-Type: application/json" \
-H "X-PAYMENT: <x402_payment_proof>" \
-d '{}'Example
Request
{
"url": "https://lowpaymentfee.com/api/v1/inbox/193",
"body": {},
"method": "POST",
"headers": {
"X-PAYMENT": "<x402_payment_proof>",
"Content-Type": "application/json"
}
}Endpoint
Quality
The endpoint is confirmed live with a valid x402 challenge and clear pricing ($0.02 USDC on Base). However, there is no OpenAPI spec, no input/output schema documentation, no usage examples, and the specific purpose of /api/v1/inbox/193 is entirely unclear beyond the generic label 'Premium API Access'. Most site pages return only a wallet-connect prompt.
Warnings
- —No OpenAPI or schema documentation available — input parameters and response format for /api/v1/inbox/193 are unknown
- —The /api, /pricing, and /README pages all return only a 'Connect wallet' prompt with no useful content
- —The purpose of the specific 'inbox/193' endpoint is unclear; it may be a generic or placeholder route
- —No rate-limit or SLA information is documented
Citations
- —Platform lists endpoints at $0.02/request with no API keys, no rate limits, and instant access on Base networkhttps://lowpaymentfee.com
- —x402 challenge returns maxAmountRequired of 20000 base units of USDC (asset 0x833589fCD6eDb6E08f4c7C32D4f71b54bdA02913) on Basehttps://lowpaymentfee.com/api/v1/inbox/193
- —Available API categories include Data & Analytics, AI & Machine Learning, Finance & Web3, and Infrastructurehttps://lowpaymentfee.com