Pay-per-request premium API collection on Base via x402 — $0.02/call in USDC.
What it does
This endpoint is part of lowpaymentfee.com, a platform offering a broad catalog of pay-per-request APIs settled via the x402 protocol on the Base network using USDC. The specific endpoint `/api/v1/collections/21` is labeled "Premium API Access" and accepts POST requests. The x402 challenge confirms it is live, requiring a maximum of 20,000 base units of USDC (0x8335…2913 on Base), which equals $0.02 per request (USDC uses 6 decimals). No API keys or rate limits are advertised; callers pay per request with no minimums or commitments.
The broader lowpaymentfee.com platform lists 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 (geocoding, validation, conversion, generation). All are priced at $0.02 per request. However, the specific functionality behind `/api/v1/collections/21` is not documented beyond the generic "Premium API Access" label, so its exact response payload and purpose are unclear.
Documentation is extremely sparse — the /docs, /api, /pricing, and /README pages all render only a "Connect wallet" prompt with no further technical detail. There is no OpenAPI spec, no request/response schema, and no usage examples available from the crawl. The endpoint is confirmed live (402 challenge captured), but the lack of documentation makes it difficult to know what data or service this specific collection endpoint returns.
Capabilities
Use cases
- —Accessing premium data or services with per-request USDC micropayments on Base
- —Integrating pay-as-you-go API calls into agent workflows without API key management
- —Programmatic access to a collection endpoint via x402 protocol
Fit
Best for
- —Developers wanting zero-commitment, per-request API access settled in USDC
- —AI agents that can handle x402 payment challenges natively
- —Users on the Base L2 network looking for low-fee API micropayments
Not for
- —Users who need detailed API documentation or response schemas before integrating
- —Applications requiring high-throughput bulk access with predictable flat-rate pricing
- —Developers without a Base-compatible USDC wallet
Quick start
curl -X POST https://lowpaymentfee.com/api/v1/collections/21 \
-H "Content-Type: application/json" \
-H "X-PAYMENT: <x402-payment-token>"Endpoint
Quality
The endpoint is confirmed live via a valid x402 402 challenge, and pricing is clear ($0.02 USDC per request). However, there is no documentation, no OpenAPI spec, no request/response schema, and no indication of what data or service this specific 'collections/21' endpoint actually returns. The docs pages are empty beyond a wallet-connect prompt. This is effectively a stub listing.
Warnings
- —No documentation available — /docs, /api, /pricing, and /README pages all show only 'Connect wallet' with no technical content
- —The exact functionality of /api/v1/collections/21 ('Premium API Access') is undocumented; it is unclear what this endpoint returns
- —No OpenAPI spec or request/response schema is provided
- —No examples of successful responses are available
Citations
- —The endpoint returns a 402 x402 challenge requiring 20000 base units of USDC on Basehttps://lowpaymentfee.com/api/v1/collections/21
- —USDC asset address is 0x833589fCD6eDb6E08f4c7C32D4f71b54bdA02913 on Basehttps://lowpaymentfee.com/api/v1/collections/21
- —All listed APIs are priced at $0.02 per request with no API keys, no rate limits, and no minimumshttps://lowpaymentfee.com
- —The platform offers APIs across Data & Analytics, AI & ML, Finance & Web3, and Infrastructure categorieshttps://lowpaymentfee.com