Pay-per-request API suite on Base via x402 — data, AI, finance, and utility endpoints at $0.02/call.
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/Web3 data, and general utility services. All endpoints are paid per-request using USDC on the Base network, with no API keys, no rate limits, and no minimum commitments required.
The specific endpoint at `/api/v1/invoices/3` is listed as "Premium API Access" and charges up to 20,000 base units of USDC (i.e., $0.02) per call via the x402 exact payment scheme. The platform advertises additional endpoints including sentiment analysis, text summarization, classification, embeddings, price feeds, exchange rates, token quotes, gas estimates, geocoding, validation, conversion, and data generation — all at the same $0.02 price point.
Documentation is extremely sparse. The docs, API, pricing, and README pages all render only a "Connect wallet" prompt with no further content. There is no OpenAPI spec, no request/response schema documentation, and no example payloads available. The x402 challenge confirms the endpoint is live and accepts POST requests with JSON responses, but the actual input parameters and response structure for this particular endpoint are unknown.
Capabilities
Use cases
- —Accessing AI inference (sentiment, summarization, classification, embeddings) without API key signup
- —Fetching real-time crypto prices, gas estimates, and exchange rates on a per-call basis
- —Running geocoding, validation, or data conversion tasks with instant crypto-settled payments
- —Exporting data or generating analytics reports via pay-as-you-go endpoints
Fit
Best for
- —Developers who want instant API access without registration or API keys
- —Agents and bots that can settle payments in USDC on Base automatically via x402
- —Projects needing low-cost, low-friction access to a variety of utility and AI endpoints
Not for
- —Users who need detailed API documentation or guaranteed SLAs before integrating
- —Applications requiring high-throughput bulk access where per-request pricing is inefficient
- —Developers without a Base-compatible USDC wallet
Quick start
curl -X POST https://lowpaymentfee.com/api/v1/invoices/3 \
-H "Content-Type: application/json" \
-H "X-PAYMENT: <x402-payment-header>" \
-d '{}'Endpoint
Quality
The x402 challenge confirms the endpoint is live and accepts POST with USDC on Base at $0.02. However, there is no OpenAPI spec, no documented request/response schemas, no examples, and all documentation pages are empty beyond a wallet-connect prompt. The actual functionality of `/api/v1/invoices/3` is unclear — the description is just 'Premium API Access' with no further detail.
Warnings
- —No API documentation available — all doc pages render only 'Connect wallet'
- —No OpenAPI or schema definitions found for any endpoint
- —The specific purpose and input/output format of /api/v1/invoices/3 is undocumented
- —The platform lists many endpoints on its landing page but none have documented schemas or examples
- —Cannot verify that advertised endpoints (AI, finance, etc.) actually function as described
Citations
- —The endpoint charges up to 20,000 base units of USDC (asset 0x8335…) on Base, equaling $0.02 per requesthttps://lowpaymentfee.com/api/v1/invoices/3
- —The platform advertises $0.02/request pricing with no API keys, no rate limits, and instant access on Basehttps://lowpaymentfee.com
- —Available API categories include Data & Analytics, AI & Machine Learning, Finance & Web3, and Infrastructurehttps://lowpaymentfee.com
- —Documentation pages (docs, API, pricing, README) render only a 'Connect wallet' prompthttps://lowpaymentfee.com/docs