Pay-per-call API platform on Base (USDC) offering data, AI, finance, and utility endpoints at $0.02/request.
What it does
lowpaymentfee.com is an x402-enabled API platform that provides a broad catalog of pay-per-request endpoints settled in USDC on the Base network. The specific endpoint at `/api/v1/keys/45` is listed as "Premium API Access" and costs up to $0.02 per call (20,000 base units of USDC with 6 decimals). Payment is handled via the x402 protocol — no API keys, accounts, or subscriptions are required; callers simply attach an X-PAYMENT header with a valid payment proof.
The wider platform advertises four endpoint categories: 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 endpoints are listed at the same $0.02/request price point.
The specific purpose of the `/api/v1/keys/45` endpoint is unclear from the available material — the description simply says "Premium API Access" with no further documentation, input schema, or example responses. There is no OpenAPI spec, no detailed docs, and the pricing/README pages require a wallet connection to view. The endpoint is confirmed live (returns a proper 402 x402 challenge), but the lack of documentation makes it difficult to know what payload to send or what response to expect.
Capabilities
Use cases
- —Accessing pay-per-request data analytics and reports without creating an account
- —Running AI inference tasks (sentiment, summarization, classification, embeddings) with per-call USDC payment
- —Fetching real-time financial data and crypto gas estimates via micropayments
- —Using utility endpoints (geocoding, validation, conversion) on a pay-as-you-go basis
Fit
Best for
- —Developers who want instant API access without signup or API key management
- —Agents and bots that can settle payments programmatically via x402 on Base
- —Low-volume or sporadic API consumers who prefer per-call pricing over subscriptions
Not for
- —High-volume production workloads where $0.02/request adds up significantly
- —Users who need detailed API documentation, SLAs, or guaranteed uptime commitments
- —Developers without a Base-compatible USDC wallet
Quick start
curl -X POST https://lowpaymentfee.com/api/v1/keys/45 \
-H "Content-Type: application/json" \
-H "X-PAYMENT: <x402-payment-proof>"Endpoint
Quality
The endpoint is confirmed live with a valid x402 402 challenge, but there is no OpenAPI spec, no documentation of request/response schemas, and the purpose of /api/v1/keys/45 specifically is undocumented. Pricing and README pages are behind a wallet-connect gate. This is effectively a stub listing.
Warnings
- —No OpenAPI or schema documentation available for this endpoint
- —The specific function of /api/v1/keys/45 ('Premium API Access') is not explained anywhere in the crawled material
- —Pricing, README, and API doc pages require wallet connection and could not be crawled
- —No example request or response payloads are available
- —The platform lists many endpoints but none have detailed documentation visible without authentication
Citations
- —The endpoint returns a valid x402 challenge with maxAmountRequired of 20000 base units of USDC on Basehttps://lowpaymentfee.com/api/v1/keys/45
- —All listed endpoints are priced at $0.02 per request with no API keys, no rate limits, and instant access on Base networkhttps://lowpaymentfee.com
- —The platform offers endpoints across Data & Analytics, AI & ML, Finance & Web3, and Infrastructure categorieshttps://lowpaymentfee.com
- —USDC asset address 0x833589fCD6eDb6E08f4c7C32D4f71b54bdA02913 on Base networkhttps://lowpaymentfee.com/api/v1/keys/45