Pay-per-call API platform on Base network via x402 — $0.02/request, no API keys required.
What it does
lowpaymentfee.com is an x402-enabled API platform that offers a broad catalog 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 via the x402 payment protocol. There are no API keys, no rate limits, and no subscription commitments — callers simply attach an X-PAYMENT header with a valid x402 payment proof to access any endpoint.
The specific endpoint at `/api/v1/transactions/171` is listed as "Premium API Access" and accepts POST requests. The x402 challenge advertises a maxAmountRequired of 20000 base units of USDC (contract 0x833589fCD6eDb6E08f4c7C32D4f71b54bdA02913 on Base), which equals $0.02 given USDC's 6 decimals. The payment is sent to address 0x1A2B13E97f5F837C8F9FA1F95a1484B7C70d85F3 with a 300-second timeout.
The broader platform advertises endpoints for sentiment analysis, text summarization, classification, embeddings, price feeds, exchange rates, token quotes, gas estimates, geocoding, validation, conversion, and generation — all at the same $0.02 price point. However, documentation beyond the landing page is extremely sparse; the docs, API, pricing, and README pages all render only a "Connect wallet" prompt with no further technical detail. No OpenAPI schema, request/response examples, or detailed endpoint documentation were found.
Capabilities
Use cases
- —Accessing AI inference (sentiment, summarization, classification, embeddings) without API key management
- —Fetching real-time crypto prices, gas estimates, and exchange rates on a per-call basis
- —Running geocoding or data validation utilities with micropayment-based access
- —Exporting data or generating analytics reports without subscription overhead
Fit
Best for
- —Agents and bots that need stateless, pay-per-call API access without credentials
- —Developers prototyping with low-cost, no-commitment API endpoints
- —Web3-native applications already operating on the Base network
Not for
- —High-volume production workloads where per-request pricing adds up quickly
- —Users who need detailed API documentation, SLAs, or guaranteed uptime
- —Teams without USDC on Base or unfamiliar with x402 payment flows
Quick start
curl -X POST https://lowpaymentfee.com/api/v1/transactions/171 \
-H "Content-Type: application/json" \
-H "X-PAYMENT: <x402-payment-proof>"Endpoint
Quality
The endpoint is live and returns a valid x402 402 challenge with clear pricing. However, documentation is essentially nonexistent — all doc/pricing/API pages show only 'Connect wallet'. No OpenAPI schema, no request/response examples, and no description of what '/api/v1/transactions/171' actually returns. The listing is largely a stub.
Warnings
- —No documentation available beyond the landing page — docs, API, pricing, and README pages all render only 'Connect wallet'
- —No OpenAPI or schema describing request parameters or response format for this endpoint
- —The endpoint path '/api/v1/transactions/171' with description 'Premium API Access' does not appear in the landing page's listed endpoints, making its actual functionality unclear
- —Cannot verify what data or service this specific endpoint provides
Citations
- —The platform advertises $0.02 per request with no API keys, no rate limits, and instant access on the Base networkhttps://lowpaymentfee.com
- —The x402 challenge shows maxAmountRequired of 20000 base units of USDC on Base with a 300-second timeouthttps://lowpaymentfee.com/api/v1/transactions/171
- —USDC asset contract on Base is 0x833589fCD6eDb6E08f4c7C32D4f71b54bdA02913https://lowpaymentfee.com/api/v1/transactions/171
- —Docs, API, pricing, and README pages render only 'Connect wallet' with no further contenthttps://lowpaymentfee.com/docs