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 "Premium API Access" via the x402 payment protocol on the Base network. The site hosts a broad catalog of pay-per-call APIs spanning data & analytics, 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 priced at $0.02 per request, settled in USDC on Base.
The specific endpoint `/api/v1/charges/368` is labeled "Premium API Access" in the x402 challenge. Its exact functionality beyond the generic label is unclear — the site does not document what this particular charge ID returns, and the crawled docs, pricing, and README pages all rendered only a wallet-connect prompt with no additional content. The x402 challenge confirms the endpoint is live, accepts POST requests, requires a maximum payment of 20,000 base units of USDC (i.e., $0.02 given 6 decimals), and responds with `application/json`.
Because the site lacks OpenAPI specs, detailed endpoint documentation, request/response schemas, or examples, the actual input parameters and output format for this endpoint remain unknown. Agents should treat this as a low-cost, keyless API call but should be prepared to discover the request format experimentally.
Capabilities
Use cases
- —Programmatic access to a pay-per-call API without managing API keys or subscriptions
- —Agent-driven workflows that need low-cost, on-demand API calls settled in USDC on Base
- —Exploring x402-protocol-based API marketplaces for data, AI, finance, or utility services
Fit
Best for
- —Developers or agents wanting keyless, pay-per-request API access
- —Low-volume or sporadic API consumers who prefer no commitments or minimums
- —x402-compatible agents that can settle USDC payments on Base
Not for
- —Users who need detailed API documentation or guaranteed SLAs before calling
- —High-volume consumers who need bulk pricing or rate-limit guarantees
- —Anyone without a Base-compatible USDC wallet
Quick start
curl -X POST https://lowpaymentfee.com/api/v1/charges/368 \
-H "Content-Type: application/json" \
-H "X-PAYMENT: <x402-payment-header>" \
-d '{}'Endpoint
Quality
The x402 challenge is live and confirms pricing and network, but the endpoint's actual functionality is undocumented. No OpenAPI spec, no request/response schema, no examples, and the docs/pricing/README pages are empty beyond a wallet-connect prompt. The 'Premium API Access' label is generic and uninformative.
Warnings
- —Endpoint functionality is unknown — 'Premium API Access' is a generic label with no documentation of inputs or outputs.
- —No OpenAPI or schema documentation available; request format must be discovered experimentally.
- —Docs, pricing, and README pages on the site render only a wallet-connect prompt with no useful content.
- —The charge ID 368 is not referenced anywhere in the site's listed API catalog, so it may be a custom or unlisted endpoint.
Citations
- —The endpoint returns a 402 x402 challenge with maxAmountRequired of 20000 base units of USDC on Basehttps://lowpaymentfee.com/api/v1/charges/368
- —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 offers APIs across Data & Analytics, AI & ML, Finance & Web3, and Infrastructure categorieshttps://lowpaymentfee.com
- —USDC asset address 0x833589fCD6eDb6E08f4c7C32D4f71b54bdA02913 on Base networkhttps://lowpaymentfee.com/api/v1/charges/368