x402-gated product inventory endpoint on Base, pay-per-request with USDC.
What it does
This endpoint at lowpaymentfee.com provides access to a product inventory resource (product ID 57) behind an x402 paywall. The endpoint accepts POST requests and returns JSON. Payment is settled on the Base network using USDC (contract 0x8335…2913) via the x402 "exact" scheme. The maximum amount required per call is 20,000 base units of USDC, which equals $0.02 USD (USDC uses 6 decimals).
The hosting site lowpaymentfee.com advertises a broad catalog of x402-gated APIs spanning data analytics, AI/ML inference, finance/Web3 data, and infrastructure utilities — all priced at $0.02 per request with no API keys, no rate limits, and no commitments. However, the specific endpoint listed here (/api/v1/products/57/inventory) is not explicitly mentioned on the site's landing page among the advertised API categories. It is described only as "Premium API Access" in the x402 challenge. No OpenAPI schema, request/response examples, or detailed documentation were found for this endpoint; the docs, pricing, and README pages all returned only a "Connect wallet" prompt with no substantive content.
Because the endpoint is live (returns a valid 402 challenge) and the pricing is clear, it is functional for agent consumption. However, the lack of documentation about what the inventory response actually contains, what POST body is expected, and what "product 57" refers to makes it difficult to use without experimentation.
Capabilities
Use cases
- —Querying inventory status for a specific product via a micropayment-gated API
- —Integrating pay-per-request product data into an agent workflow without API keys
- —Demonstrating x402 protocol payment flows on Base with USDC
Fit
Best for
- —Agents that need keyless, pay-per-call access to product inventory data
- —Developers experimenting with x402 protocol integrations on Base
- —Workflows requiring no subscription or rate-limit constraints
Not for
- —Users who need detailed documentation or schema before integrating
- —Bulk inventory queries across many products (only product 57 is exposed at this path)
- —Non-crypto payment workflows — requires USDC on Base
Quick start
curl -X POST https://lowpaymentfee.com/api/v1/products/57/inventory \
-H "Content-Type: application/json" \
-H "X-PAYMENT: <x402-payment-token>"Endpoint
Quality
The endpoint is live and returns a valid x402 challenge with clear pricing ($0.02 USDC on Base). However, there is no OpenAPI schema, no request/response examples, no documentation beyond a wallet-connect prompt, and the specific endpoint is not described on the landing page. The purpose of 'product 57 inventory' is entirely opaque.
Warnings
- —No documentation available — docs, pricing, and README pages all return only 'Connect wallet' with no content.
- —The specific endpoint /api/v1/products/57/inventory is not listed among the site's advertised APIs.
- —No request body schema or response schema is provided; callers must guess the expected input.
- —The meaning of 'product 57' and what 'inventory' data is returned are unknown.
Citations
- —The endpoint returns a valid x402 challenge with maxAmountRequired of 20000 base units of USDC on Base network.https://lowpaymentfee.com/api/v1/products/57/inventory
- —The site advertises $0.02 per request pricing with no API keys, no rate limits, and instant access on Base network.https://lowpaymentfee.com
- —USDC asset contract on Base is 0x833589fCD6eDb6E08f4c7C32D4f71b54bdA02913.https://lowpaymentfee.com/api/v1/products/57/inventory