Pay-per-call API platform on Base via x402 — $0.02/request, no API keys required.
What it does
lowpaymentfee.com is an x402-enabled API platform that offers a broad catalog of endpoints spanning data analytics, AI/ML inference, finance/Web3 data, and utility services. Every endpoint is priced at $0.02 per request, paid in USDC on the Base network via the x402 payment protocol. There are no API keys, no rate limits, and no sign-up — callers simply attach an X-PAYMENT header with a valid x402 payment proof.
The specific endpoint at `/api/v1/payments/39` is listed as "Premium API Access" and accepts POST requests. The x402 challenge advertises a maxAmountRequired of 20000 base units of USDC (contract 0x8335…2913 on Base), which equals $0.02 given USDC's 6 decimals. The platform also hosts endpoints for sentiment analysis, text summarization, classification, embeddings, price feeds, exchange rates, token quotes, gas estimates, geocoding, validation, conversion, and generation — all at the same $0.02 price point.
Documentation is extremely sparse: the /docs, /pricing, /api, and /README pages all render only a "Connect wallet" prompt with no further content. There is no OpenAPI spec, no request/response schema documentation, and no usage examples available from the crawled material. The endpoint is confirmed live (returns 402 with a well-formed x402 challenge), but without documentation it is unclear what request body this particular endpoint expects or what response it returns.
Capabilities
Use cases
- —Agents that need on-demand API access without pre-registration or API key management
- —Pay-per-call AI inference (sentiment, summarization, classification, embeddings)
- —Fetching real-time crypto token quotes and gas estimates
- —Geocoding and data conversion utilities with zero commitment
Fit
Best for
- —AI agents needing frictionless, keyless API access via x402
- —Developers who want to avoid subscription commitments for low-volume usage
- —Web3-native applications that can settle payments in USDC on Base
Not for
- —High-volume production workloads where per-call pricing at $0.02 adds up quickly
- —Users who need detailed API documentation or guaranteed SLAs before integrating
- —Applications that cannot handle x402 payment flows or USDC on Base
Quick start
curl -X POST https://lowpaymentfee.com/api/v1/payments/39 \
-H "Content-Type: application/json" \
-H "X-PAYMENT: <x402-payment-proof>" \
-d '{}'Endpoint
Quality
The endpoint is confirmed live with a valid x402 402 challenge and pricing is clear ($0.02 USDC on Base). However, there is no OpenAPI spec, no request/response schema, and all documentation pages return only a wallet-connect prompt. The specific purpose of /api/v1/payments/39 ('Premium API Access') is undocumented, making it effectively a stub listing.
Warnings
- —No API documentation available — /docs, /pricing, /api, and /README all render only 'Connect wallet'
- —No OpenAPI or JSON schema describing request/response formats for this endpoint
- —The purpose and expected input of /api/v1/payments/39 ('Premium API Access') is unclear — it may be a generic or placeholder endpoint
- —Cannot verify what data or service this specific endpoint actually provides
Citations
- —All endpoints priced at $0.02 per request with no API keys, no rate limits, and instant access on Base networkhttps://lowpaymentfee.com
- —x402 challenge returns maxAmountRequired of 20000 base units of USDC (asset 0x833589fCD6eDb6E08f4c7C32D4f71b54bdA02913) on Basehttps://lowpaymentfee.com/api/v1/payments/39
- —Platform offers endpoints across Data & Analytics, AI & ML, Finance & Web3, and Infrastructure categorieshttps://lowpaymentfee.com