Pay-per-call API platform on Base (USDC) offering data, AI, finance, and utility endpoints at $0.02/request.
What it does
lowpaymentfee.com is an x402-enabled API platform that hosts a collection of endpoints spanning data & analytics, AI & machine learning, finance & Web3, and infrastructure utilities. All endpoints are paid per-request using USDC on the Base network via the x402 protocol — no API keys, no rate limits, and no subscriptions required.
The specific endpoint at `/api/v1/inbox/187` is listed as "Premium API Access" and accepts POST requests. Its x402 challenge advertises a maximum cost of 20,000 base units of USDC (0x8335…2913 on Base), which equals $0.02 per request (USDC uses 6 decimals). The broader platform lists roughly 16 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 at the same $0.02 price point.
Documentation is minimal. The crawled /api, /pricing, and /README pages all returned only a "Connect wallet" prompt with no further content. There is no OpenAPI spec, no request/response schema documentation, and no usage examples available. The endpoint is live (returns a proper 402 challenge), but without documentation it is unclear what request body `/api/v1/inbox/187` expects or what response it returns.
Capabilities
Use cases
- —Accessing AI inference (sentiment, summarization, classification, embeddings) without API key management
- —Fetching real-time financial data (prices, exchange rates, gas estimates) on a per-call basis
- —Running utility operations (geocoding, validation, conversion) with instant crypto micropayments
- —Integrating pay-as-you-go analytics and data export into agent workflows
Fit
Best for
- —Agents or developers who want keyless, pay-per-call API access settled in USDC on Base
- —Projects needing low-cost ($0.02) micropayment-gated endpoints without subscriptions
- —Web3-native applications that prefer on-chain payment over traditional billing
Not for
- —Users who need detailed API documentation, schemas, or guaranteed SLAs before integrating
- —High-volume consumers who would benefit from bulk pricing or subscription plans
- —Developers without access to USDC on the Base network
Quick start
curl -X POST https://lowpaymentfee.com/api/v1/inbox/187 \
-H "Content-Type: application/json" \
-H "X-PAYMENT: <x402-payment-token>" \
-d '{}'Endpoint
Quality
The endpoint is live and returns a valid x402 402 challenge, confirming pricing and network. However, there is no OpenAPI spec, no request/response schema, no documentation beyond a landing page listing, and the specific purpose of /api/v1/inbox/187 is entirely unclear. This is effectively a stub listing.
Warnings
- —No API documentation, OpenAPI spec, or request/response schemas available
- —The purpose and expected input of /api/v1/inbox/187 ('Premium API Access') is not described anywhere
- —All non-root crawled pages (/api, /pricing, /README) returned only 'Connect wallet' with no content
- —Cannot verify what any of the listed endpoints actually return without documentation or example responses
Citations
- —The platform lists ~16 endpoints across Data & Analytics, AI & ML, Finance & Web3, and Infrastructure categories, all at $0.02/requesthttps://lowpaymentfee.com
- —Pricing is $0.02 per request with no API keys, no rate limits, and instant access on the Base networkhttps://lowpaymentfee.com
- —The x402 challenge for /api/v1/inbox/187 specifies maxAmountRequired of 20000 base units of USDC on Basehttps://lowpaymentfee.com/api/v1/inbox/187
- —USDC asset address on Base is 0x833589fCD6eDb6E08f4c7C32D4f71b54bdA02913https://lowpaymentfee.com/api/v1/inbox/187