x402-gated premium API access on Base, pay $0.02 per request in USDC — no API keys required.
What it does
This endpoint at lowpaymentfee.com provides a collection of pay-per-call APIs gated via the x402 protocol on the Base network. The specific endpoint `/api/v1/trades/9` is listed as "Premium API Access" and accepts POST requests. Payment is settled in USDC (contract 0x833589fCD6eDb6E08f4c7C32D4f71b54bdA02913) on Base, with a maximum amount of 20,000 base units (i.e., $0.02 per request, since USDC uses 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 lowpaymentfee.com platform advertises endpoints across several 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 are priced at $0.02 per request. However, the specific `/api/v1/trades/9` endpoint does not clearly map to any of these listed categories, and no documentation describes what data or functionality it returns.
The endpoint is confirmed live — it returns a proper HTTP 402 challenge with x402 version 1 headers. Documentation on the site is extremely thin; the docs, API, pricing, and README pages all render only a "Connect wallet" prompt with no further content. There is no OpenAPI spec, no request/response schema, and no example payloads available.
Capabilities
Use cases
- —Programmatic access to premium data or trade information without managing API keys
- —Agent-driven workflows that need on-demand paid API calls settled in USDC on Base
- —Integrating pay-per-use endpoints into Web3 applications
Fit
Best for
- —Developers wanting zero-friction API access without subscriptions or API key management
- —AI agents that can autonomously pay for API calls via x402
- —Users already holding USDC on the Base network
Not for
- —Users who need detailed API documentation or response schemas before integrating
- —Applications requiring free or high-volume bulk access at lower marginal cost
- —Developers not set up for crypto payments on Base
Quick start
# The endpoint requires an x402 payment proof in the X-PAYMENT header.
# Using curl to see the 402 challenge:
curl -X POST https://lowpaymentfee.com/api/v1/trades/9 \
-H "Content-Type: application/json"
# Returns 402 with x402 challenge. Attach a valid X-PAYMENT header to complete the call.Endpoint
Quality
The endpoint is live and returns a valid x402 402 challenge, but there is no documentation, no OpenAPI spec, no request/response examples, and the specific endpoint path '/api/v1/trades/9' is not described anywhere on the site. The docs pages are empty. This is effectively a stub listing.
Warnings
- —No documentation available — docs, API, pricing, and README pages all show only 'Connect wallet' with no content.
- —The endpoint path /api/v1/trades/9 does not appear in the site's listed API catalog, so its purpose is unknown.
- —No request body schema or response schema is documented or discoverable.
- —No OpenAPI specification found.
Citations
- —The endpoint returns a 402 challenge with x402 version 1, accepting USDC on Base with maxAmountRequired of 20000 base unitshttps://lowpaymentfee.com/api/v1/trades/9
- —USDC asset contract is 0x833589fCD6eDb6E08f4c7C32D4f71b54bdA02913 on Basehttps://lowpaymentfee.com/api/v1/trades/9
- —All listed APIs are priced at $0.02 per request with no API keys, no rate limits, and instant access on Base networkhttps://lowpaymentfee.com
- —The site lists APIs across Data & Analytics, AI & ML, Finance & Web3, and Infrastructure categorieshttps://lowpaymentfee.com