Pay-per-request API suite on Base (USDC) — data, AI, finance, and utility endpoints at $0.02/call.
What it does
lowpaymentfee.com hosts a collection of x402-enabled API endpoints settled in USDC on the Base network. The specific endpoint at `/api/v1/inbox/12` is labeled "Premium API Access" and costs up to $0.02 per request (maxAmountRequired of 20,000 base units of USDC with 6 decimals). Payment is handled via the x402 protocol: callers attach an `X-PAYMENT` header with a signed payment proof, and the server fulfills the request once payment is verified. No API keys, accounts, or rate limits are advertised.
The broader platform advertises four categories of endpoints: Data & Analytics (metrics, reports, data export, insights), AI & Machine Learning (sentiment analysis, text summarization, classification, embeddings), Finance & Web3 (price feeds, exchange rates, token quotes, gas estimates), and Infrastructure utilities (geocoding, validation, conversion, generation). All are listed at $0.02 per request. Each endpoint accepts POST requests and returns `application/json`.
The specific functionality behind `/api/v1/inbox/12` is not documented beyond the generic "Premium API Access" label. There is no OpenAPI spec, no request/response schema, and the crawled docs pages (pricing, README, /api) all resolve to a wallet-connect prompt with no additional content. Prospective callers should be aware that the actual behavior of this particular endpoint is unclear from available documentation.
Capabilities
Use cases
- —Programmatic access to pay-per-use API endpoints without account registration
- —Agent-driven API consumption with on-chain USDC micropayments
- —Integrating x402-compatible payment flows into automated workflows
Fit
Best for
- —Developers or agents that already hold USDC on Base and want frictionless API access
- —Use cases requiring no-signup, no-rate-limit API calls
- —Testing x402 payment protocol integrations
Not for
- —Users who need detailed API documentation or guaranteed SLAs before calling
- —Callers who cannot transact in USDC on the Base network
- —High-volume batch workloads where $0.02/request adds up significantly
Quick start
curl -X POST https://lowpaymentfee.com/api/v1/inbox/12 \
-H "Content-Type: application/json" \
-H "X-PAYMENT: <signed-x402-payment-proof>" \
-d '{}'Endpoint
Quality
The endpoint is live (returns a valid 402 x402 challenge) and pricing is clear ($0.02 USDC on Base). However, there is no OpenAPI spec, no request/response schema, no documentation of what /api/v1/inbox/12 actually does, and crawled pages beyond the landing page are empty wallet-connect stubs. The listing is effectively a stub.
Warnings
- —No documentation exists for the specific endpoint /api/v1/inbox/12 — its actual functionality is unknown.
- —No OpenAPI or request/response schema is available for any endpoint on this platform.
- —Crawled /pricing, /README, and /api pages contain no useful content (only 'Connect wallet').
- —The 'Premium API Access' label is generic and does not describe what the endpoint returns.
Citations
- —Endpoint returns a 402 x402 challenge with maxAmountRequired of 20000 base units of USDC on Basehttps://lowpaymentfee.com/api/v1/inbox/12
- —USDC asset contract on Base: 0x833589fCD6eDb6E08f4c7C32D4f71b54bdA02913https://lowpaymentfee.com/api/v1/inbox/12
- —All listed endpoints priced at $0.02 per request with no API keys, no rate limits, and instant accesshttps://lowpaymentfee.com
- —Platform offers endpoints in Data & Analytics, AI & ML, Finance & Web3, and Infrastructure categorieshttps://lowpaymentfee.com