Pay-per-call API platform on Base (USDC) — $0.02/request, no keys or rate limits.
What it does
lowpaymentfee.com is an x402-enabled API marketplace that hosts a broad set of endpoints spanning data analytics, AI/ML inference, finance/Web3 data, and infrastructure utilities. Every endpoint is priced at $0.02 per request, payable in USDC on the Base network via the x402 protocol. There are no API keys, no rate limits, and no signup — callers simply attach an x402 payment header to each request.
The specific endpoint `/api/v1/inbox/35` is listed as "Premium API Access" but its exact functionality is not documented beyond that label. The provider's landing page catalogs roughly 16 other endpoints (metrics, reports, data export, insights, sentiment analysis, text summarization, classification, embeddings, price feeds, exchange rates, token quotes, gas estimates, geocoding, validation, conversion, generation), all at the same $0.02 price point. The probe confirms this endpoint is live, returning a valid 402 challenge with `maxAmountRequired` of 20000 base units of USDC (6 decimals), which equals $0.02.
Because the `/api/v1/inbox/35` endpoint lacks its own documentation, input schema, or example responses, it is unclear what data or service it actually provides. The broader platform advertises instant access and settlement on Base, but no OpenAPI spec, detailed docs, or example payloads were found for any endpoint.
Capabilities
Use cases
- —Programmatic access to a pay-per-call API without managing API keys or subscriptions
- —Agent-driven workflows that need on-demand endpoint access settled in USDC on Base
- —Testing x402 payment flows against a live, low-cost endpoint
Fit
Best for
- —Developers or agents wanting zero-signup, per-request API access
- —x402 protocol integration testing at low cost ($0.02/call)
- —Scenarios where avoiding API key management is important
Not for
- —Users who need detailed documentation or guaranteed SLAs before integrating
- —High-volume batch workloads where $0.02/request adds up without volume discounts
- —Anyone requiring fiat-only payment — this endpoint requires USDC on Base
Quick start
curl -X POST https://lowpaymentfee.com/api/v1/inbox/35 \
-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 documentation, no OpenAPI spec, no input/output schema, and no description of what '/api/v1/inbox/35' actually does beyond the generic label 'Premium API Access'. This is effectively a stub listing.
Warnings
- —No documentation found for /api/v1/inbox/35 — its actual functionality is unknown.
- —No OpenAPI spec or input/output schema available for any endpoint on the platform.
- —The endpoint name 'inbox/35' suggests a resource-specific or user-specific route; it may not be generally useful.
- —The /api, /pricing, and /README pages all returned only a 'Connect wallet' prompt with no useful content.
Citations
- —The endpoint returns a valid x402 402 challenge with maxAmountRequired of 20000 base units of USDC on Basehttps://lowpaymentfee.com/api/v1/inbox/35
- —USDC asset contract 0x833589fCD6eDb6E08f4c7C32D4f71b54bdA02913 on Base networkhttps://lowpaymentfee.com/api/v1/inbox/35
- —All listed endpoints priced at $0.02 per request with no API keys, no rate limits, and instant accesshttps://lowpaymentfee.com
- —Platform offers endpoints across Data & Analytics, AI & ML, Finance & Web3, and Infrastructure categorieshttps://lowpaymentfee.com