x402-gated premium API endpoint on Base, payable in USDC at $0.02 per call.
What it does
This x402-protocol endpoint at lowpaymentfee.com provides a pay-per-call "Premium API Access" service. Each request is gated by an x402 payment challenge requiring 20,000 base units of USDC (USD Coin) on the Base network, which equals $0.02 per call (USDC uses 6 decimals). The endpoint accepts POST requests and returns application/json responses.
The payment is settled on-chain to address 0x1A2B13E97f5F837C8F9FA1F95a1484B7C70d85F3 using the exact payment scheme. The maximum timeout for payment verification is 300 seconds (5 minutes). The x402 challenge is version 1 and the USDC asset contract is the canonical Base USDC at 0x833589fCD6eDb6E08f4c7C32D4f71b54bdA02913.
Beyond the x402 challenge metadata, very little is known about what this endpoint actually does. The crawled pages (API docs, pricing, README) all returned only a "Connect wallet" prompt with no further documentation, schema, or usage examples. The endpoint is live and responding with a valid 402 challenge, but the actual functionality behind the paywall is undocumented. Callers should be aware that the specific behavior, input format, and response structure are unknown.
Capabilities
Use cases
- —Accessing a premium API resource behind a $0.02 USDC paywall on Base
- —Demonstrating x402 protocol payment flows with a low-cost endpoint
- —Integrating pay-per-call API access into agent workflows
Fit
Best for
- —Developers experimenting with x402 protocol integrations
- —Agents needing low-cost pay-per-call API access on Base
- —Testing USDC micropayment flows
Not for
- —Users who need detailed API documentation before purchasing
- —Applications requiring known, well-documented response schemas
- —High-throughput use cases where per-call on-chain settlement adds latency
Quick start
curl -X POST https://lowpaymentfee.com/api/v1/inbox/192 \
-H "Content-Type: application/json" \
-H "X-PAYMENT: <x402-payment-token>" \
-d '{}'Endpoint
Quality
The endpoint is live and returns a valid x402 challenge, confirming pricing and network details. However, there is zero documentation: all crawled pages show only 'Connect wallet' with no API docs, schemas, examples, or description of what the endpoint actually does. This is effectively a stub listing.
Warnings
- —No documentation available — all crawled pages (API, pricing, README) return only 'Connect wallet'
- —Unknown request body schema — no input format documented
- —Unknown response body schema — no output format documented
- —Actual functionality behind the paywall is completely undocumented
- —The specific inbox ID (192) in the URL suggests this may be a user-specific or resource-specific endpoint
Citations
- —Endpoint returns a valid x402 challenge with status 402https://lowpaymentfee.com/api/v1/inbox/192
- —Payment requires 20,000 base units of USDC on Base network ($0.02)https://lowpaymentfee.com/api/v1/inbox/192
- —USDC asset contract is 0x833589fCD6eDb6E08f4c7C32D4f71b54bdA02913https://lowpaymentfee.com/api/v1/inbox/192
- —All crawled documentation pages show only 'Connect wallet'https://lowpaymentfee.com/api