Pay-per-call API platform on Base (USDC) via x402 — $0.02/request, no API keys required.
What it does
lowpaymentfee.com is an x402-enabled API platform that offers a variety of endpoints across data analytics, AI/ML inference, finance/Web3, and infrastructure utilities. All endpoints are pay-per-request using USDC on the Base network, settled via the x402 protocol. There are no API keys, no rate limits, and no subscription commitments — callers simply attach an X-PAYMENT header with a valid payment proof to each request.
The specific endpoint at `/api/v1/payments/20` is listed as "Premium API Access" and requires a maximum of 20,000 base units of USDC (i.e., $0.02) per call. The platform advertises a uniform $0.02 price across all its endpoints. Categories of available APIs include: metrics and reports (analytics), sentiment analysis, text summarization, classification, and embeddings (AI/ML), price feeds, exchange rates, token quotes, and gas estimates (finance/crypto), and geocoding, validation, conversion, and generation (utilities).
Documentation beyond the landing page is sparse — the /docs, /pricing, /api, and /README pages all render only a "Connect wallet" prompt with no additional technical detail. There is no OpenAPI spec, no request/response schema documentation, and no example payloads available from the crawl. The endpoint is confirmed live (returns a proper 402 x402 challenge), but the lack of documentation makes it difficult to know what request body to send or what response to expect.
Capabilities
Use cases
- —Agents that need on-demand AI inference (sentiment, summarization, classification, embeddings) without managing API keys
- —Fetching real-time crypto token quotes, gas estimates, or exchange rates with per-call payment
- —Geocoding or data validation as a utility service paid in USDC on Base
- —Exporting analytics data or generating reports via pay-per-request endpoints
Fit
Best for
- —AI agents and bots that can settle x402 payments autonomously
- —Developers who want zero-signup, pay-as-you-go API access
- —Low-volume or bursty workloads where subscriptions are wasteful
Not for
- —Users who need detailed API documentation or OpenAPI specs before integrating
- —High-volume production workloads that benefit from bulk pricing or rate guarantees
- —Users without USDC on the Base network
Quick start
curl -X POST https://lowpaymentfee.com/api/v1/payments/20 \
-H "Content-Type: application/json" \
-H "X-PAYMENT: <x402-payment-proof>" \
-d '{}'Endpoint
Quality
The endpoint is confirmed live with a valid 402 x402 challenge and pricing is clear ($0.02 USDC on Base). However, there is no OpenAPI spec, no request/response schema, no documentation beyond a landing page, and no examples. The docs, pricing, and README pages are all empty wallet-connect stubs. This is effectively a stub listing.
Warnings
- —No OpenAPI or schema documentation available — request/response formats are unknown
- —All documentation pages (/docs, /pricing, /api, /README) return only a 'Connect wallet' prompt with no content
- —The specific purpose of the /api/v1/payments/20 endpoint labeled 'Premium API Access' is unclear — it may be a generic payment test endpoint rather than a functional API
- —No examples of successful responses are available from any source
Citations
- —Uniform pricing of $0.02 per request across all endpoints, no API keys, no rate limitshttps://lowpaymentfee.com
- —Endpoint returns 402 with x402 challenge requiring 20000 base units of USDC on Base networkhttps://lowpaymentfee.com/api/v1/payments/20
- —USDC asset contract on Base: 0x833589fCD6eDb6E08f4c7C32D4f71b54bdA02913https://lowpaymentfee.com/api/v1/payments/20
- —Available API categories include Data & Analytics, AI & Machine Learning, Finance & Web3, and Infrastructurehttps://lowpaymentfee.com