Pay-per-call API platform on Base network via x402 — $0.02/request in USDC.
What it does
lowpaymentfee.com is an x402-enabled API platform that offers a broad set of endpoints spanning data analytics, AI/ML inference, finance/Web3 data, and utility services. Every endpoint costs $0.02 per request, paid in USDC on the Base network with no API keys, no rate limits, and no commitments required. The x402 protocol handles payment inline: callers attach a payment header to each HTTP request and receive the response immediately upon settlement.
The specific endpoint at `/api/v1/transactions/201` is listed as "Premium API Access" and returns a 402 challenge requesting up to 20,000 base units of USDC (0x8335…2913 on Base). Since USDC uses 6 decimals, this equals $0.02 per call. The challenge specifies the `exact` payment scheme with a 300-second timeout. The endpoint accepts POST requests and returns `application/json`.
The broader platform advertises additional endpoints including sentiment analysis, text summarization, classification, embeddings, price feeds, exchange rates, token quotes, gas estimates, geocoding, validation, conversion, and generation utilities — all at the same $0.02 price point. However, documentation beyond the landing page is essentially empty (all sub-pages just show "Connect wallet"), so the actual behavior, request schemas, and response formats for any of these endpoints are undocumented.
Capabilities
Use cases
- —Agents that need on-demand API access without pre-registration or API keys
- —Programmatic access to utility endpoints (geocoding, validation, conversion) with per-call billing
- —Testing x402 payment protocol integrations against a live endpoint
Fit
Best for
- —Developers exploring x402 payment-gated APIs
- —AI agents that can settle USDC payments on Base per request
- —Users who want zero-commitment, pay-as-you-go API access
Not for
- —Users needing detailed API documentation or guaranteed SLAs
- —High-volume use cases where $0.02/request adds up significantly
- —Users without a Base-network USDC wallet
Quick start
curl -X POST https://lowpaymentfee.com/api/v1/transactions/201 \
-H "Content-Type: application/json" \
-H "X-PAYMENT: <x402-payment-token>"Endpoint
Quality
The endpoint is live and returns a valid x402 402 challenge with clear pricing. However, there is no OpenAPI spec, no documentation of request/response schemas, and all doc pages are empty ('Connect wallet'). The actual functionality behind 'Premium API Access' at /api/v1/transactions/201 is unclear — the name is generic and no examples exist.
Warnings
- —All documentation pages (/docs, /api, /pricing, /README) are empty, showing only 'Connect wallet'
- —No OpenAPI or schema documentation available for any endpoint
- —The specific purpose of /api/v1/transactions/201 ('Premium API Access') is not explained anywhere
- —No request body schema or response schema documented — callers cannot know what to send or expect back
- —The platform lists many endpoints on its landing page but none have documented behavior
Citations
- —The endpoint returns a 402 challenge requesting 20,000 base units of USDC on Base networkhttps://lowpaymentfee.com/api/v1/transactions/201
- —All endpoints cost $0.02 per request with no API keys, no rate limits, and instant accesshttps://lowpaymentfee.com
- —The platform offers endpoints across Data & Analytics, AI & ML, Finance & Web3, and Infrastructure categorieshttps://lowpaymentfee.com
- —USDC asset address is 0x833589fCD6eDb6E08f4c7C32D4f71b54bdA02913 on Basehttps://lowpaymentfee.com/api/v1/transactions/201