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 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 with no API keys, no rate limits, and no upfront commitments. The x402 payment challenge is live and returns a standard 402 response with an "exact" payment scheme.
The specific endpoint at `/api/v1/transactions/356` is listed as "Premium API Access" and accepts POST requests. The probe confirms it is live, returning a valid x402 challenge requesting up to 20,000 base units of USDC (0x8335…2913 on Base), which equals $0.02 given USDC's 6 decimals. Payment is sent to address 0x1A2B13E97f5F837C8F9FA1F95a1484B7C70d85F3 with a 300-second timeout.
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 — all at the same $0.02 price point. However, documentation pages (/docs, /pricing, /README) returned only a "Connect wallet" prompt with no substantive content, so the actual behavior and response schemas of these endpoints remain undocumented.
Capabilities
Use cases
- —Accessing AI inference endpoints (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 USDC micropayments
- —Exporting data or generating analytics reports via pay-as-you-go endpoints
Fit
Best for
- —Developers wanting zero-signup, pay-per-use API access
- —Agents that can settle x402 payments in USDC on Base
- —Projects needing a variety of lightweight utility and AI endpoints without rate limits
Not for
- —Users who need detailed API documentation or response schemas before integrating
- —High-volume consumers who would benefit from bulk pricing or subscription plans
- —Developers without a Base-compatible USDC wallet
Quick start
# The endpoint returns 402 with an x402 challenge.
# After constructing the X-PAYMENT header per x402 spec:
curl -X POST https://lowpaymentfee.com/api/v1/transactions/356 \
-H "Content-Type: application/json" \
-H "X-PAYMENT: <signed-payment-payload>"Endpoint
Quality
The x402 challenge is live and pricing is clear ($0.02 USDC on Base), but there is no OpenAPI schema, no response examples, and all documentation pages return only a wallet-connect prompt. The actual functionality behind 'Premium API Access' at /api/v1/transactions/356 is unexplained — the endpoint name and description are generic. This is effectively a stub listing.
Warnings
- —No API documentation available — /docs, /pricing, and /README pages all return only 'Connect wallet' with no content.
- —The purpose and expected input/output of /api/v1/transactions/356 ('Premium API Access') is not described anywhere.
- —No OpenAPI spec or response schema is provided for any endpoint.
- —The broad catalog of endpoints (AI, finance, geo, etc.) is advertised but none have verifiable documentation.
Citations
- —Endpoint returns a live 402 x402 challenge with maxAmountRequired of 20000 base units of USDC on Basehttps://lowpaymentfee.com/api/v1/transactions/356
- —Platform advertises $0.02 per request with no API keys, no rate limits, and instant access on Base networkhttps://lowpaymentfee.com
- —USDC asset contract on Base is 0x833589fCD6eDb6E08f4c7C32D4f71b54bdA02913https://lowpaymentfee.com/api/v1/transactions/356
- —Documentation pages (/docs, /pricing, /README) returned only 'Connect wallet' with no substantive contenthttps://lowpaymentfee.com/docs