Pay-per-call API access on Base via x402 — $0.02/request in USDC, no keys required.
What it does
lowpaymentfee.com offers a collection of pay-per-request API endpoints settled via the x402 protocol on the Base network using USDC. The specific endpoint at `/api/v1/keys/35` is labeled "Premium API Access" and charges up to 20,000 base units of USDC (i.e., $0.02) per call. The broader platform advertises endpoints spanning 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 at the same $0.02/request price point.
Payment is handled entirely through the x402 payment header mechanism: callers send a cryptographic payment proof in the HTTP request header, and the endpoint processes the request without requiring traditional API keys, accounts, or rate limits. Settlement occurs on the Base L2 network to the USDC contract at 0x833589fCD6eDb6E08f4c7C32D4f71b54bdA02913. The endpoint was confirmed live, returning a proper 402 challenge with x402 version 1.
Note that while the landing page lists many endpoints across multiple categories, the specific endpoint being listed here (`/api/v1/keys/35`) is described only as "Premium API Access" with no further documentation on what data or functionality it returns. There is no OpenAPI schema, no example responses, and the crawled docs/pricing/README pages all returned only a "Connect wallet" prompt with no additional content. The actual behavior of this particular endpoint remains unclear.
Capabilities
Use cases
- —Accessing premium API functionality with per-request USDC micropayments on Base
- —Agent-driven workflows that need keyless, on-demand API access
- —Programmatic access to paid endpoints without subscription or account setup
Fit
Best for
- —Developers or agents with USDC on Base who want frictionless pay-per-call access
- —Use cases requiring no sign-up, no API key, and no rate limits
- —Experimenting with x402 protocol-based API payments
Not for
- —Users who need detailed documentation or guaranteed SLAs before integrating
- —High-volume consumers who would benefit from bulk/subscription pricing rather than per-call fees
- —Users without a Base-compatible wallet or USDC holdings
Quick start
curl -X POST https://lowpaymentfee.com/api/v1/keys/35 \
-H "Content-Type: application/json" \
-H "X-PAYMENT: <x402-payment-proof>"Endpoint
Quality
The endpoint is confirmed live with a valid 402 challenge and clear pricing ($0.02 USDC on Base). However, there is no OpenAPI schema, no documentation of request/response formats, no example payloads, and the specific functionality of /api/v1/keys/35 is undocumented beyond the label 'Premium API Access'. The docs, pricing, and README pages returned no useful content.
Warnings
- —No OpenAPI or schema documentation available for this endpoint
- —The actual functionality of /api/v1/keys/35 is unknown — 'Premium API Access' is the only description
- —Docs, pricing, and README pages returned only 'Connect wallet' with no substantive content
- —No example request or response bodies are available
Citations
- —The endpoint returns a 402 challenge with x402 version 1, accepting USDC on Base with maxAmountRequired of 20000 base units ($0.02)https://lowpaymentfee.com/api/v1/keys/35
- —The platform advertises $0.02/request pricing with no API keys, no rate limits, and instant access on the Base networkhttps://lowpaymentfee.com
- —USDC asset contract on Base is 0x833589fCD6eDb6E08f4c7C32D4f71b54bdA02913https://lowpaymentfee.com/api/v1/keys/35
- —The platform lists endpoints across data & analytics, AI & ML, finance & Web3, and infrastructure categorieshttps://lowpaymentfee.com