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 broad collection of endpoints spanning data analytics, AI/ML inference, finance/Web3 market data, and general-purpose utilities. Every endpoint is priced at $0.02 per request, settled in USDC on the Base network via the x402 payment protocol. There are no API keys, no rate limits, and no minimum commitments — callers simply attach an x402 payment header to each request.
The specific endpoint at `/api/v1/inbox/194` is listed as "Premium API Access" but its exact functionality is not documented beyond that label. The broader platform advertises endpoints such as sentiment analysis, text summarization, classification, embeddings, price feeds, exchange rates, token quotes, gas estimates, geocoding, validation, conversion, and data generation — all at the same $0.02 price point. The probe confirms this endpoint is live, returning a 402 challenge requesting 20,000 base units of USDC (6 decimals = $0.02) on Base.
Because the crawled pages beyond the landing page returned only "Connect wallet" prompts with no further documentation, there is no OpenAPI schema, no request/response examples, and no detailed description of what `/api/v1/inbox/194` specifically returns. Callers should treat this as a minimally documented endpoint until the provider publishes more detail.
Capabilities
Use cases
- —Accessing AI inference (sentiment, summarization, classification, embeddings) without API key management
- —Fetching real-time crypto quotes, gas estimates, and exchange rates on a per-call basis
- —Running geocoding, validation, or data conversion tasks with instant micropayments
- —Prototyping agent workflows that need low-friction, pay-as-you-go API access
Fit
Best for
- —Developers wanting zero-signup, pay-per-use API access
- —AI agents that can settle x402 payments autonomously on Base
- —Projects needing low-cost ($0.02) utility and data endpoints without rate limits
Not for
- —Users who need detailed API documentation and guaranteed SLAs before integrating
- —High-volume production workloads that benefit from bulk pricing or subscription plans
- —Teams that cannot transact in USDC on the Base network
Quick start
curl -X POST https://lowpaymentfee.com/api/v1/inbox/194 \
-H "Content-Type: application/json" \
-H "X-PAYMENT: <x402-payment-header>" \
-d '{}'Endpoint
Quality
The endpoint is confirmed live via a valid 402 challenge, and the landing page provides a clear pricing model ($0.02/request in USDC on Base). However, there is no OpenAPI schema, no request/response examples, and no documentation for what /api/v1/inbox/194 specifically does — 'Premium API Access' is an opaque label. The crawled subpages returned no useful content.
Warnings
- —The specific functionality of /api/v1/inbox/194 ('Premium API Access') is undocumented — it is unclear what data or service it provides.
- —No OpenAPI schema, request format, or response examples are available.
- —Subpages (/api, /pricing, /README) returned only 'Connect wallet' with no documentation content.
- —The platform lists many endpoints on its landing page but none link to detailed docs.
Citations
- —Endpoint returns a 402 challenge requesting 20,000 base units of USDC on Base (= $0.02)https://lowpaymentfee.com/api/v1/inbox/194
- —USDC asset address 0x833589fCD6eDb6E08f4c7C32D4f71b54bdA02913 on Base networkhttps://lowpaymentfee.com/api/v1/inbox/194
- —Platform advertises $0.02/request, no API keys, no rate limits, instant access on Base networkhttps://lowpaymentfee.com
- —Available API categories include Data & Analytics, AI & Machine Learning, Finance & Web3, and Infrastructurehttps://lowpaymentfee.com