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/78` is labeled "Premium API Access" and charges up to 20,000 base units of USDC (i.e., $0.02) per call via the x402 exact payment scheme. No API keys, rate limits, or upfront commitments are required — callers simply attach an X-PAYMENT header with a valid x402 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 listed endpoints share the same $0.02/request pricing.
This particular endpoint (`/api/v1/keys/78`) does not have public documentation explaining its request or response schema beyond the x402 challenge metadata. The challenge confirms it accepts HTTP POST, returns `application/json`, and is discoverable. Without further docs or an OpenAPI spec, the exact input parameters and response structure remain unknown.
Capabilities
Use cases
- —Programmatic access to premium API functionality with per-request USDC micropayments
- —Agent-driven workflows that need on-demand API access without pre-registration or API keys
- —Integrating pay-as-you-go endpoints into crypto-native applications on Base
Fit
Best for
- —Developers wanting zero-commitment, pay-per-use API access
- —AI agents that can settle x402 payments autonomously on Base
- —Projects needing low-cost micropayment-gated endpoints
Not for
- —Users who need detailed API documentation or OpenAPI specs before integrating
- —Applications requiring free or subscription-based API access
- —Non-crypto workflows that cannot settle USDC on Base
Quick start
curl -X POST https://lowpaymentfee.com/api/v1/keys/78 \
-H "Content-Type: application/json" \
-H "X-PAYMENT: <x402-payment-proof>"Endpoint
Quality
The x402 challenge is live and confirms pricing and settlement details, but there is no OpenAPI spec, no documentation of request/response schemas, and the crawled pages beyond the homepage returned only 'Connect wallet' with no useful content. The purpose of the /api/v1/keys/78 endpoint specifically is unclear beyond its generic 'Premium API Access' label.
Warnings
- —No OpenAPI or schema documentation available for this endpoint
- —The exact purpose and input/output format of /api/v1/keys/78 is undocumented
- —The broader platform lists many endpoints but none have public specs or examples
- —Crawled /api, /pricing, and /README pages returned no meaningful content
Citations
- —The endpoint returns a 402 x402 challenge with maxAmountRequired of 20000 base units of USDC on Basehttps://lowpaymentfee.com/api/v1/keys/78
- —All listed endpoints are priced at $0.02 per request with no API keys, rate limits, or commitmentshttps://lowpaymentfee.com
- —The platform offers endpoints across Data & Analytics, AI & ML, Finance & Web3, and Infrastructure categorieshttps://lowpaymentfee.com
- —USDC asset address is 0x833589fCD6eDb6E08f4c7C32D4f71b54bdA02913 on Base networkhttps://lowpaymentfee.com/api/v1/keys/78