x402-gated Stripe invoice endpoint on Base, pay-per-call with USDC.
What it does
This endpoint at lowpaymentfee.com provides access to a Stripe invoice resource (invoice ID 15) behind an x402 payment wall. The endpoint accepts POST requests and returns JSON. Payment is settled on the Base network using USDC (contract 0x8335…2913) with a maximum cost of $0.02 per request (20,000 base units at 6 decimals). No API keys or rate limits are required — callers simply attach an X-PAYMENT header with a valid x402 payment proof.
The broader lowpaymentfee.com platform advertises a suite of pay-per-call APIs spanning data analytics, AI/ML inference (sentiment analysis, summarization, classification, embeddings), finance/crypto market data, and utility services (geocoding, validation, conversion, generation), all priced at $0.02 per request. However, the specific endpoint listed here (/api/v1/stripe/invoices/15) is not described on the landing page among those categories, and its exact response payload is undocumented. The description provided by the x402 challenge is simply "Premium API Access."
Documentation is extremely sparse — the /docs, /api, /pricing, and /README pages all render only a "Connect wallet" prompt with no further technical detail. There is no OpenAPI spec, no request/response schema beyond the minimal outputSchema in the x402 challenge, and no usage examples. The endpoint is confirmed live (returns a well-formed 402 challenge), but the lack of documentation makes it difficult to know what data is returned or what input parameters are expected.
Capabilities
Use cases
- —Retrieving Stripe invoice data via a crypto-settled pay-per-call model
- —Demonstrating x402 protocol integration for agent-purchasable endpoints
- —Accessing premium API resources without traditional API key management
Fit
Best for
- —Developers experimenting with x402 payment protocol on Base
- —Agents that can autonomously pay for API calls with USDC
- —Use cases needing keyless, pay-as-you-go API access
Not for
- —Users who need detailed API documentation or guaranteed SLAs
- —Production systems requiring well-documented request/response schemas
- —Users without USDC on the Base network
Quick start
curl -X POST https://lowpaymentfee.com/api/v1/stripe/invoices/15 \
-H "Content-Type: application/json" \
-H "X-PAYMENT: <x402-payment-proof>"Endpoint
Quality
The endpoint is live and returns a valid x402 challenge, but documentation is essentially nonexistent — no OpenAPI spec, no request/response examples, and the docs pages are empty. The specific endpoint (/api/v1/stripe/invoices/15) is not described among the platform's advertised APIs, making its purpose unclear.
Warnings
- —No documentation available — /docs, /api, /pricing, and /README pages all show only 'Connect wallet'
- —No OpenAPI or schema describing request parameters or response format
- —This specific endpoint (/api/v1/stripe/invoices/15) is not listed among the platform's advertised API categories
- —Response payload and required POST body are unknown
Citations
- —The endpoint returns a valid x402 challenge with maxAmountRequired of 20000 base units in USDC on Basehttps://lowpaymentfee.com/api/v1/stripe/invoices/15
- —The platform advertises $0.02/request pricing with no API keys, no rate limits, and instant access on Base networkhttps://lowpaymentfee.com
- —USDC asset contract is 0x833589fCD6eDb6E08f4c7C32D4f71b54bdA02913 on Basehttps://lowpaymentfee.com/api/v1/stripe/invoices/15