Pay-per-call API suite on Base (USDC) covering AI, analytics, finance, and utilities at $0.02/request.
What it does
lowpaymentfee.com is an x402-enabled API platform that offers a broad collection of endpoints spanning data analytics, AI/ML inference, finance/crypto 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 signup — callers simply attach an X-PAYMENT header with a valid x402 payment proof.
The probed endpoint (`/api/private`) returns a standard x402 challenge with a maxAmountRequired of 20,000 base units of USDC (6 decimals), which equals $0.02. The site advertises four endpoint 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 utilities (geocoding, validation, conversion, generation). Each of these 16 listed endpoints is priced identically at $0.02.
Documentation is extremely thin — the /docs, /pricing, /api, and /README pages all render only a "Connect wallet" prompt with no further technical detail. There is no OpenAPI spec, no request/response schema documentation, and no usage examples available from the crawl. The actual behavior, accepted parameters, and response formats of each endpoint are unknown beyond the endpoint paths and brief labels shown on the landing page.
Capabilities
Use cases
- —Running sentiment analysis or text classification without managing API keys or subscriptions
- —Fetching real-time crypto gas estimates or token price quotes with per-call payment
- —Geocoding addresses or validating data via utility endpoints paid in USDC
- —Generating text embeddings for search or recommendation pipelines
- —Exporting analytics data or insights on demand
Fit
Best for
- —Developers who want instant, keyless API access paid per request in crypto
- —Agents or bots that can settle x402 payments on Base automatically
- —Low-volume or sporadic API consumers who don't want subscriptions
Not for
- —High-volume production workloads needing guaranteed SLAs and detailed documentation
- —Users without a Base-compatible USDC wallet or x402 client
- —Developers who need well-documented request/response schemas before integrating
Quick start
# Requires an x402-compatible client that attaches payment headers
curl -X POST https://lowpaymentfee.com/api/v2/ai/sentiment \
-H "Content-Type: application/json" \
-H "X-PAYMENT: <x402_payment_proof>" \
-d '{"text": "This product is amazing!"}'Example
Request
{
"text": "This product is amazing!"
}Endpoint
Quality
The endpoint is live and returns a valid x402 challenge, and the landing page lists 16 endpoints with consistent pricing. However, there is zero documentation beyond endpoint names — no OpenAPI spec, no request/response schemas, no examples, and all doc pages just show 'Connect wallet'. The actual functionality of each endpoint is unverifiable.
Warnings
- —No OpenAPI or schema documentation available — all doc pages render only 'Connect wallet'
- —Request and response formats for all endpoints are completely undocumented
- —The probed path /api/private does not match any of the 16 listed endpoint paths; its specific purpose is unclear
- —Actual functionality behind each endpoint label is unverified — could be stubs
Citations
- —The site lists 16 endpoints across four categories (Data & Analytics, AI & ML, Finance & Web3, Infrastructure) each priced at $0.02/requesthttps://lowpaymentfee.com
- —Pricing is $0.02 per request with no API keys, no rate limits, and instant access on Base networkhttps://lowpaymentfee.com
- —The x402 challenge returns maxAmountRequired of 20000 base units of USDC (asset 0x833589fCD6eDb6E08f4c7C32D4f71b54bdA02913) on Basehttps://lowpaymentfee.com/api/private
- —Documentation pages (/docs, /pricing, /api, /README) all render only 'Connect wallet' with no technical contenthttps://lowpaymentfee.com/docs