x402-gated API platform on Base offering data, AI, finance, and utility endpoints at $0.02/request via USDC.
What it does
lowpaymentfee.com is an x402-protocol API marketplace that gates a variety of endpoints behind per-request USDC micropayments on the Base network. The specific endpoint at `/api/v1/inbox/118` is listed as "Premium API Access" and costs up to $0.02 per call (maxAmountRequired of 20,000 base units of USDC, which has 6 decimals = $0.02). Payment is made via the x402 exact scheme with no API keys, no rate limits, and no upfront commitments required.
The broader 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 endpoints are uniformly priced at $0.02 per request and settle in USDC on Base to a single payTo address.
Note that the specific endpoint `/api/v1/inbox/118` does not clearly map to any of the named API categories on the landing page. Its exact functionality is not documented beyond the generic "Premium API Access" label. There is no OpenAPI schema, no request/response examples, and the pricing, README, and API documentation pages all resolve to a minimal "Connect wallet" prompt with no further detail. Prospective callers should test the endpoint to determine what it actually returns.
Capabilities
Use cases
- —Paying per-request for AI inference (sentiment, summarization, classification, embeddings) without API key management
- —Fetching real-time financial data (prices, exchange rates, gas estimates) via micropayments
- —Accessing utility services like geocoding, validation, and data conversion on demand
- —Integrating agent-purchasable endpoints into autonomous workflows using x402 protocol
Fit
Best for
- —AI agents that need keyless, pay-per-call API access
- —Developers prototyping with low-commitment, no-subscription APIs
- —Web3-native applications already operating on Base with USDC
Not for
- —High-volume production workloads where per-request pricing at $0.02 adds up quickly
- —Users who need detailed API documentation and guaranteed SLAs before integrating
- —Applications requiring non-USDC or non-Base payment rails
Quick start
curl -X POST https://lowpaymentfee.com/api/v1/inbox/118 \
-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 schema, no request/response examples, no documentation beyond a generic label, and the specific function of /api/v1/inbox/118 is unknown. The docs pages (pricing, README, API) all resolve to empty 'Connect wallet' stubs.
Warnings
- —The endpoint path /api/v1/inbox/118 does not match any of the named APIs on the landing page; its actual functionality is undocumented.
- —No OpenAPI spec, request schema, or response schema is available.
- —Documentation pages (/pricing, /README, /api) contain no useful content beyond 'Connect wallet'.
- —The platform lists many endpoints but none have detailed docs; treat all advertised capabilities as unverified.
Citations
- —The endpoint returns a 402 x402 challenge with maxAmountRequired of 20000 base units of USDC on Basehttps://lowpaymentfee.com/api/v1/inbox/118
- —USDC asset address 0x833589fCD6eDb6E08f4c7C32D4f71b54bdA02913 on Base networkhttps://lowpaymentfee.com/api/v1/inbox/118
- —All endpoints priced at $0.02 per request with no API keys, no rate limits, and instant accesshttps://lowpaymentfee.com
- —Platform offers Data & Analytics, AI & ML, Finance & Web3, and Infrastructure API categorieshttps://lowpaymentfee.com