x402-gated Stripe invoice endpoint on Base, pay-per-call with USDC.
What it does
This endpoint at lowpaymentfee.com exposes a Stripe invoice resource (`/api/v1/stripe/invoices/38`) behind an x402 paywall. When called without payment, it returns a 402 challenge requesting USDC on the Base network. The maximum amount required per call is 20,000 base units of USDC (0.02 USD), consistent with the site-wide $0.02/request pricing advertised by the provider.
The provider, lowpaymentfee.com, offers a broader catalog of pay-per-call APIs spanning data analytics, AI/ML inference (sentiment analysis, summarization, classification, embeddings), finance/crypto market data, and utility services. All endpoints share the same $0.02 USDC pricing and x402 payment scheme on Base. This specific endpoint appears to be a Stripe invoice resource, though the exact response payload is undocumented — no OpenAPI spec, examples, or detailed docs were found during crawling (most pages only rendered a "Connect wallet" prompt).
The endpoint is live and responds with a well-formed x402 v1 challenge. Payment is settled on-chain via USDC (contract 0x8335…2913) on Base to address 0x1A2B…85F3. The payment scheme is "exact" with a 300-second timeout. No API keys or rate limits are advertised. Documentation is extremely sparse, so the actual request format and response schema remain unknown.
Capabilities
Use cases
- —Retrieving or interacting with a Stripe invoice programmatically via a crypto-paywall
- —Agent-driven invoice access without traditional API key provisioning
- —Demonstrating x402 payment protocol integration with Stripe billing data
Fit
Best for
- —Developers exploring x402 protocol integrations
- —Agents that need keyless, pay-per-call access to invoice data
- —Projects already using USDC on Base for micro-payments
Not for
- —Production invoice management requiring documented, stable APIs
- —Users who need detailed response schema guarantees before integration
- —High-volume batch invoice processing (each call costs $0.02 on-chain)
Quick start
curl -X POST https://lowpaymentfee.com/api/v1/stripe/invoices/38
# Returns 402 with x402 challenge; attach X-PAYMENT header with signed USDC payment to access.Endpoint
Quality
The endpoint is live and returns a valid x402 challenge, but there is no OpenAPI spec, no documentation of request/response schemas, and no examples. Most crawled pages only show a 'Connect wallet' prompt. The purpose of this specific Stripe invoice endpoint is unclear beyond its title.
Warnings
- —No OpenAPI or schema documentation available for this endpoint
- —Response payload structure is completely undocumented
- —Most documentation pages render only a 'Connect wallet' prompt with no useful content
- —The specific purpose of /api/v1/stripe/invoices/38 is unclear — it may be a demo or placeholder
- —No information on what POST body (if any) is expected
Citations
- —The endpoint returns a 402 challenge requesting 20,000 base units of USDC on Base networkhttps://lowpaymentfee.com/api/v1/stripe/invoices/38
- —Site-wide pricing is $0.02 per request with no API keys, no rate limitshttps://lowpaymentfee.com
- —USDC asset contract is 0x833589fCD6eDb6E08f4c7C32D4f71b54bdA02913 on Basehttps://lowpaymentfee.com/api/v1/stripe/invoices/38