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 provides a broad collection of endpoints spanning data analytics, AI/ML inference, finance/Web3 data, and general utility services. All endpoints are pay-per-request using the x402 protocol, settling payments in USDC on the Base network. There are no API keys, no rate limits, and no subscription commitments — callers simply attach an x402 payment header to each request.
The specific endpoint at `/api/v1/inbox/92` is listed as "Premium API Access" and requires up to 20,000 base units of USDC (i.e., $0.02) per call. The platform's landing page advertises a uniform $0.02 per request across all endpoints. Categories of available APIs include: metrics and reports (Data & Analytics), sentiment analysis, text summarization, classification, and embeddings (AI & ML), price feeds, exchange rates, token quotes, and gas estimates (Finance & Web3), and geocoding, validation, conversion, and generation utilities (Infrastructure).
The probe confirmed the endpoint is live, returning a proper 402 challenge with x402 version 1. The payment is directed to address `0x1A2B13E97f5F837C8F9FA1F95a1484B7C70d85F3` using the USDC contract on Base (`0x833589fCD6eDb6E08f4c7C32D4f71b54bdA02913`). No OpenAPI schema, detailed documentation, or example request/response payloads were found in the crawl, so the exact input parameters and response format for this particular endpoint remain unknown.
Capabilities
Use cases
- —Agents needing on-demand AI inference (sentiment, summarization, classification, embeddings) without managing API keys
- —Fetching real-time crypto token quotes, gas estimates, or exchange rates via micropayment
- —Running geocoding, data validation, or format conversion as a utility service
- —Exporting analytics data or generating reports on a per-request payment basis
Fit
Best for
- —AI agents that need keyless, pay-per-call access to diverse utility and AI endpoints
- —Developers prototyping with low-cost, no-commitment API access on Base
- —Web3-native applications that can settle USDC payments on Base L2
Not for
- —High-volume production workloads where per-request pricing at $0.02 adds up significantly
- —Users who cannot transact in USDC on the Base network
- —Applications requiring detailed SLAs, guaranteed uptime, or rate-limit guarantees
Quick start
curl -X POST https://lowpaymentfee.com/api/v1/inbox/92 \
-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, but there is no OpenAPI schema, no documentation beyond the landing page listing, and no example request/response payloads. The specific purpose of /api/v1/inbox/92 ('Premium API Access') is entirely opaque — it could be any of the advertised services or something else. Pricing is clear but functionality is not.
Warnings
- —No OpenAPI or schema documentation available for any endpoint
- —The specific purpose and input/output format of /api/v1/inbox/92 is unknown — 'Premium API Access' is a generic label
- —No detailed docs, README, or API reference pages were accessible (all returned only 'Connect wallet')
- —Cannot verify what data or service this specific endpoint actually provides
Citations
- —Uniform pricing of $0.02 per request across all endpoints, no API keys, no rate limitshttps://lowpaymentfee.com
- —Endpoint returns 402 with maxAmountRequired of 20000 base units USDC (=$0.02) on Base networkhttps://lowpaymentfee.com/api/v1/inbox/92
- —Available API categories include Data & Analytics, AI & ML, Finance & Web3, and Infrastructurehttps://lowpaymentfee.com
- —USDC asset contract on Base: 0x833589fCD6eDb6E08f4c7C32D4f71b54bdA02913https://lowpaymentfee.com/api/v1/inbox/92