x402-gated Stripe invoice endpoint on Base, paid per-call in USDC.
What it does
This endpoint at lowpaymentfee.com exposes a specific Stripe invoice resource (`/api/v1/stripe/invoices/122`) behind an x402 paywall. The provider operates a broader platform offering dozens of pay-per-request API endpoints across data analytics, AI/ML inference, finance, and utility categories, all settled on the Base network using USDC via the x402 protocol.
The probed endpoint returns a valid x402 challenge (version 1, scheme "exact") requesting up to 20,000 base units of USDC (0x8335…) on Base. Since USDC uses 6 decimals, this translates to $0.02 per request — consistent with the site's advertised flat pricing of $0.02/request across all endpoints. Payment is sent to address 0x1A2B13E97f5F837C8F9FA1F95a1484B7C70d85F3 with a 300-second timeout. The endpoint accepts POST requests and returns application/json.
Documentation is extremely thin: the docs, API, pricing, and README pages all render only a "Connect wallet" prompt with no substantive content. There is no OpenAPI spec, no request/response schema, and no description of what data this particular invoice endpoint actually returns. The provider advertises no API keys, no rate limits, and instant access, but the specific behavior of the `/stripe/invoices/122` resource is undocumented.
Capabilities
Use cases
- —Retrieving Stripe invoice data via a crypto-settled paywall
- —Demonstrating x402 protocol payment flows for API access
- —Agent-driven invoice lookups without traditional API key management
Fit
Best for
- —Developers experimenting with x402 payment protocol
- —Agents that can settle USDC payments on Base for per-call API access
- —Use cases requiring keyless, pay-as-you-go API consumption
Not for
- —Production invoice management requiring documented schemas and SLAs
- —Users who need traditional API key authentication or OAuth
- —High-volume batch processing where per-call fees add up quickly
Quick start
curl -X POST https://lowpaymentfee.com/api/v1/stripe/invoices/122 \
-H "X-PAYMENT: <x402-payment-token>" \
-H "Content-Type: application/json"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 spec, no request/response schema, no documentation beyond a wallet-connect prompt, and no explanation of what data the Stripe invoice endpoint actually returns. The listing is essentially a stub.
Warnings
- —No OpenAPI or schema documentation available — request and response formats are unknown
- —Docs, API, pricing, and README pages all render only 'Connect wallet' with no content
- —The specific purpose and data returned by /api/v1/stripe/invoices/122 is undocumented
- —The endpoint references a hardcoded invoice ID (122), suggesting it may be a demo or single-resource endpoint
Citations
- —The endpoint returns a valid x402 challenge with maxAmountRequired of 20000 base units of USDC on Basehttps://lowpaymentfee.com/api/v1/stripe/invoices/122
- —The site advertises $0.02 per request flat pricing across all endpointshttps://lowpaymentfee.com
- —The provider claims no API keys, no rate limits, and instant accesshttps://lowpaymentfee.com
- —Docs, pricing, API, and README pages render only a 'Connect wallet' prompthttps://lowpaymentfee.com/docs