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 provides a broad catalog of pay-per-request endpoints settled in USDC on the Base network. The specific endpoint at `/api/v1/inbox/140` is listed as "Premium API Access" and costs up to $0.02 per request (20,000 base units of USDC with 6 decimals). No API keys or rate limits are advertised; callers authenticate purely via the x402 payment header.
The platform advertises four categories of APIs: 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 listed endpoints share the same $0.02/request pricing.
However, the specific `/api/v1/inbox/140` endpoint does not clearly map to any of the named API categories on the landing page. Its purpose is described only as "Premium API Access" with no further documentation, input schema, or example responses available. The crawled docs, pricing, and README pages all returned only a "Connect wallet" prompt with no additional content. Without documentation or an OpenAPI spec, the actual functionality of this particular endpoint remains unclear.
Capabilities
Use cases
- —Accessing pay-per-call data and analytics endpoints without API key management
- —Running AI inference tasks (sentiment, summarization, classification, embeddings) on a per-request basis
- —Fetching real-time crypto and finance data (prices, exchange rates, gas estimates)
- —Using utility services like geocoding, validation, and data conversion
Fit
Best for
- —Agents or developers who want zero-commitment, pay-as-you-go API access
- —Use cases requiring no rate limits and instant access without signup
- —Crypto-native workflows that can settle payments in USDC on Base
Not for
- —Users needing detailed API documentation or guaranteed SLAs before integrating
- —High-volume production workloads where $0.02/request adds up significantly
- —Anyone unable to transact in USDC on the Base network
Quick start
curl -X POST https://lowpaymentfee.com/api/v1/inbox/140 \
-H "Content-Type: application/json" \
-H "X-PAYMENT: <x402-payment-token>" \
-d '{}'Endpoint
Quality
The endpoint is live (returns a valid 402 x402 challenge) and pricing is clear ($0.02 USDC on Base). However, there is no OpenAPI spec, no documentation beyond the landing page, no input/output schema, and the specific /api/v1/inbox/140 path is not described anywhere on the site. The actual functionality of this endpoint is unknown.
Warnings
- —The endpoint path /api/v1/inbox/140 does not appear in the site's listed API catalog — its actual functionality is undocumented.
- —No OpenAPI spec, request schema, or response examples are available.
- —Docs, pricing, and README pages returned only 'Connect wallet' with no usable content.
- —Without knowing what this endpoint does, callers cannot form valid requests.
Citations
- —The endpoint returns a 402 x402 challenge with maxAmountRequired of 20000 base units of USDC on Basehttps://lowpaymentfee.com/api/v1/inbox/140
- —All listed APIs are priced at $0.02 per request with no API keys, no rate limits, and instant access on the Base networkhttps://lowpaymentfee.com
- —The platform offers Data & Analytics, AI & ML, Finance & Web3, and Infrastructure API categorieshttps://lowpaymentfee.com
- —USDC asset address 0x833589fCD6eDb6E08f4c7C32D4f71b54bdA02913 on Base networkhttps://lowpaymentfee.com/api/v1/inbox/140