x402-gated premium API access on Base, paid per-request in USDC.
What it does
This endpoint at lowpaymentfee.com provides "Premium API Access" behind an x402 paywall. The specific resource path (`/api/v1/stripe/invoices/168`) suggests it returns invoice or billing-related data, though the exact response payload is not documented. Payment is settled on the Base network using USDC (contract 0x8335…2913) via the x402 "exact" scheme.
The x402 challenge advertises a maxAmountRequired of 20,000 base units. Since USDC uses 6 decimals, this converts to $0.02 per request — consistent with the site's uniform $0.02/request pricing across all endpoints. The provider emphasizes a no-API-key, no-rate-limit, pay-per-use model with instant access.
lowpaymentfee.com also hosts a broader catalog of x402-gated endpoints spanning data analytics, AI/ML inference (sentiment analysis, summarization, classification, embeddings), finance/crypto market data, and utility services (geocoding, validation, conversion, generation) — all at the same $0.02/request price point. However, this specific listing covers only the `/api/v1/stripe/invoices/168` resource. Documentation beyond the landing page is extremely sparse; the docs, API, pricing, and README pages all render only a "Connect wallet" prompt with no additional technical detail.
Capabilities
Use cases
- —Retrieving invoice or billing data on a per-request basis without API key management
- —Programmatic access to premium content gated behind x402 micropayments
- —Agent-driven workflows that need to pay for and consume API data autonomously
Fit
Best for
- —AI agents that can settle x402 payments in USDC on Base
- —Developers wanting zero-signup, pay-per-use API access
- —Workflows requiring on-demand invoice or billing lookups
Not for
- —Users who need detailed API documentation or response schemas before integrating
- —High-volume consumers who prefer subscription or bulk pricing
- —Anyone without a Base-compatible USDC wallet
Quick start
curl -X POST https://lowpaymentfee.com/api/v1/stripe/invoices/168 \
-H "X-PAYMENT: <x402-payment-token>" \
-H "Content-Type: application/json"Endpoint
Quality
The endpoint is live (402 challenge captured) and pricing is clear ($0.02/request in USDC on Base). However, there is no OpenAPI schema, no documented request/response format, no examples, and all documentation pages render only a wallet-connect prompt. The specific purpose of the /stripe/invoices/168 path is unclear — it could be a demo or placeholder resource. Effectively a stub listing.
Warnings
- —No API documentation available — docs, pricing, and README pages all show only 'Connect wallet'
- —The specific resource path /api/v1/stripe/invoices/168 is not listed on the provider's landing page catalog, making its purpose unclear
- —No request or response schema is documented; integration requires trial-and-error
- —The endpoint path references a hardcoded invoice ID (168), which may be a static demo resource rather than a general-purpose API
Citations
- —maxAmountRequired is 20000 base units of USDC on Base networkhttps://lowpaymentfee.com/api/v1/stripe/invoices/168
- —USDC contract address is 0x833589fCD6eDb6E08f4c7C32D4f71b54bdA02913 on Basehttps://lowpaymentfee.com/api/v1/stripe/invoices/168
- —All listed endpoints are priced at $0.02 per request with no API keys, no rate limits, and instant accesshttps://lowpaymentfee.com
- —The site offers endpoints across Data & Analytics, AI & ML, Finance & Web3, and Infrastructure categorieshttps://lowpaymentfee.com