Pay-per-call premium API on Base via x402 — $0.02/request in USDC, no API keys required.
What it does
lowpaymentfee.com hosts a collection of pay-per-request API endpoints accessible via the x402 payment protocol on the Base network. This specific endpoint (`/api/endpoint-58`) is labeled "Premium API Access" and accepts USDC payments on Base at a maximum cost of $0.02 per request (20,000 base units of USDC with 6 decimals). No API keys, rate limits, or upfront commitments are required — callers simply attach an X-PAYMENT header with a valid x402 payment proof.
The broader site advertises endpoints across four 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. However, this particular endpoint path (`/api/endpoint-58`) does not correspond to any of the named endpoints on the site's landing page, so its exact functionality is unclear.
The endpoint is live and returns a valid x402 402 challenge. Payment settles in USDC (contract `0x8335…2913`) on Base to address `0x1A2B…85F3`. The x402 version is 1 with the "exact" payment scheme and a 300-second timeout. Documentation beyond the landing page is essentially empty (all subpages just show "Connect wallet"), so there is no schema, example request/response, or detailed usage guide available.
Capabilities
Use cases
- —Accessing premium API functionality with per-request USDC micropayments on Base
- —Agent-driven workflows that need keyless, on-demand API access
- —Testing x402 payment protocol integrations against a live endpoint
Fit
Best for
- —Developers experimenting with x402 payment flows
- —AI agents that can autonomously pay for API calls via crypto
- —Users who want no-signup, no-key API access
Not for
- —Users needing detailed API documentation or guaranteed SLAs
- —Anyone without a Base-compatible USDC wallet
- —Production workloads requiring well-documented request/response schemas
Quick start
curl -X POST https://lowpaymentfee.com/api/endpoint-58 \
-H "Content-Type: application/json" \
-H "X-PAYMENT: <x402-payment-proof>"Endpoint
Quality
The endpoint is live and returns a valid x402 challenge, but there is no documentation, no OpenAPI schema, no example requests or responses, and the endpoint path does not match any named service on the site. Functionality is entirely unknown beyond the label 'Premium API Access'.
Warnings
- —Endpoint path /api/endpoint-58 does not match any of the named endpoints listed on the site's landing page — actual functionality is unknown.
- —All documentation pages (/docs, /api, /pricing, /README) return only 'Connect wallet' with no usable content.
- —No request or response schema is available; callers cannot know what to send or what to expect back.
- —No OpenAPI spec or ai-plugin manifest found.
Citations
- —The endpoint returns a valid x402 402 challenge with USDC on Base, maxAmountRequired 20000 (=$0.02)https://lowpaymentfee.com/api/endpoint-58
- —Site advertises $0.02/request pricing across Data & Analytics, AI & ML, Finance & Web3, and Infrastructure categorieshttps://lowpaymentfee.com
- —No API keys, no rate limits, instant access advertisedhttps://lowpaymentfee.com
- —USDC asset contract is 0x833589fCD6eDb6E08f4c7C32D4f71b54bdA02913 on Basehttps://lowpaymentfee.com/api/endpoint-58