Pay-per-request API collection on Base via x402 — data, AI, finance, and utility endpoints at $0.02/call.
What it does
lowpaymentfee.com hosts a collection of pay-per-request API endpoints accessible via the x402 payment protocol on the Base network. The specific endpoint at `/api/v1/collections/50` is described as "Premium API Access" and accepts payment in USDC (contract 0x8335…2913 on Base). The maximum amount required per call is 20,000 base units of USDC, which at 6 decimals equals $0.02 per request.
The broader platform advertises four categories of APIs: 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 $0.02 per request with no API keys, no rate limits, and no minimum commitments required.
Documentation is extremely sparse — the docs, API, pricing, and README pages all render only a "Connect wallet" prompt with no further content. There is no OpenAPI schema, no request/response examples, and no detailed documentation available from the crawl. The `/api/v1/collections/50` endpoint appears to be a bundled or collection-level access point, but its exact behavior and response format are unknown beyond the x402 challenge metadata indicating it returns `application/json` via HTTP POST.
Capabilities
Use cases
- —Accessing AI inference endpoints (sentiment, summarization, classification, embeddings) without API key management
- —Fetching real-time financial data such as token quotes, gas estimates, and exchange rates on a per-request basis
- —Running data analytics queries and exporting data with pay-as-you-go pricing
- —Using utility services like geocoding, validation, and conversion without subscriptions
Fit
Best for
- —Agents or applications that need low-friction, keyless API access paid in crypto
- —Developers who want pay-per-use pricing without rate limits or commitments
- —Web3-native workflows that can settle micropayments in USDC on Base
Not for
- —Users who need detailed API documentation or guaranteed SLAs before integrating
- —High-volume consumers who would benefit from bulk pricing or subscription plans
- —Teams that cannot transact in USDC on the Base network
Quick start
curl -X POST https://lowpaymentfee.com/api/v1/collections/50 \
-H "Content-Type: application/json" \
-H "X-PAYMENT: <x402-payment-token>" \
-d '{}'Endpoint
Quality
The x402 challenge is live and confirms pricing and payment details, but documentation is effectively nonexistent — every doc/pricing/README page shows only 'Connect wallet'. No OpenAPI schema, no request/response examples, and the purpose of the /collections/50 endpoint specifically is unclear. This is essentially a stub listing.
Warnings
- —Documentation pages (docs, pricing, README, api) all render only 'Connect wallet' with no usable content
- —No OpenAPI or schema available — request and response formats are unknown
- —The specific behavior of /api/v1/collections/50 vs individual endpoints is undocumented
- —No examples of actual API responses are available from any source
Citations
- —The endpoint returns a 402 x402 challenge with maxAmountRequired of 20000 base units of USDC on Basehttps://lowpaymentfee.com/api/v1/collections/50
- —USDC asset contract on Base is 0x833589fCD6eDb6E08f4c7C32D4f71b54bdA02913https://lowpaymentfee.com/api/v1/collections/50
- —All listed endpoints are priced at $0.02 per request with no API keys, no rate limits, and instant accesshttps://lowpaymentfee.com
- —The platform offers APIs across Data & Analytics, AI & ML, Finance & Web3, and Infrastructure categorieshttps://lowpaymentfee.com