x402-gated API inbox endpoint on Base, paying $0.02 per request in USDC.
What it does
This endpoint at `/api/v1/inbox/166` is part of the lowpaymentfee.com platform, which offers a collection of x402-protocol pay-per-request APIs spanning data & analytics, AI & machine learning, finance & Web3, and infrastructure utilities. All endpoints on the platform are priced at $0.02 per request, settled in USDC on the Base network with no API keys, rate limits, or commitments required.
The specific `/api/v1/inbox/166` path is labeled "Premium API Access" but its exact functionality is not documented beyond that label. The x402 challenge confirms it is live, accepts POST requests, and requires a payment of 20,000 base units of USDC (0x8335…2913 on Base, 6 decimals = $0.02) per call. The response MIME type is `application/json`. No request body schema or response schema is provided, so the precise input/output contract is unknown.
The broader platform advertises endpoints for sentiment analysis, text summarization, classification, embeddings, price feeds, exchange rates, geocoding, validation, conversion, and data export — all at the same $0.02 price point. However, this specific inbox endpoint does not map to any of those documented categories, and no further documentation was found for it.
Capabilities
Use cases
- —Accessing a gated API resource with per-call USDC micropayments on Base
- —Integrating pay-as-you-go API calls into an agent workflow without API keys
- —Testing x402 protocol payment flows against a live endpoint
Fit
Best for
- —Developers experimenting with x402 pay-per-request protocols
- —Agents that need keyless, on-demand API access settled in USDC
- —Low-volume or sporadic API consumers who prefer no subscriptions
Not for
- —Users who need detailed documentation or guaranteed SLAs before integrating
- —High-volume consumers who would benefit from bulk pricing or rate agreements
- —Anyone requiring non-crypto payment methods
Quick start
curl -X POST https://lowpaymentfee.com/api/v1/inbox/166 \
-H "Content-Type: application/json" \
-H "X-PAYMENT: <x402-payment-token>" \
-d '{}'Endpoint
Quality
The endpoint is live and returns a valid x402 challenge, but there is no documentation for what /api/v1/inbox/166 actually does — no request schema, no response schema, no examples. The 'Premium API Access' label is generic and uninformative. The broader site lists many endpoints but none matching this path.
Warnings
- —No documentation exists for the /api/v1/inbox/166 endpoint — its purpose and expected request/response format are unknown.
- —The endpoint path does not appear in the platform's own listed API catalog, raising questions about its intended use.
- —No OpenAPI spec, no request body schema, and no response examples are available.
- —The /pricing and /README pages returned only a 'Connect wallet' prompt with no useful content.
Citations
- —The platform advertises $0.02 per request with no API keys, no rate limits, and instant access on the Base network.https://lowpaymentfee.com
- —The x402 challenge shows maxAmountRequired of 20000 base units of USDC (asset 0x833589fCD6eDb6E08f4c7C32D4f71b54bdA02913) on Base, equaling $0.02.https://lowpaymentfee.com/api/v1/inbox/166
- —The platform lists endpoints for analytics, AI/ML, finance/Web3, and infrastructure utilities.https://lowpaymentfee.com