Pay-per-request API suite on Base (USDC) covering analytics, AI, finance, and utilities 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-purpose utilities. Every endpoint is priced at $0.02 per request, settled in USDC on the Base network. There are no API keys, no rate limits, and no minimum commitments — callers simply attach an x402 payment header to each request.
The specific endpoint at `/api/v1/carts/53` is listed as "Premium API Access" and returns a 402 challenge requesting up to 20,000 base units of USDC (i.e., $0.02) on Base. The payment scheme is "exact" with a 300-second timeout. The broader platform advertises additional endpoints for 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, /pricing, /api, 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 usage examples available from the crawl. The actual functionality behind each endpoint is unclear beyond the short labels on the landing page.
Capabilities
Use cases
- —Agent-driven data retrieval with per-call USDC micropayments
- —On-demand AI inference (sentiment, summarization, classification, embeddings) without API keys
- —Fetching real-time crypto quotes and gas estimates via x402
- —Geocoding and data conversion as a pay-as-you-go utility
Fit
Best for
- —Developers wanting zero-signup, pay-per-request API access
- —AI agents that can settle x402 payments in USDC on Base
- —Prototyping workflows that need cheap, keyless API calls
Not for
- —Production workloads requiring documented request/response schemas and SLAs
- —Users without a Base-compatible USDC wallet
- —High-volume use cases where per-request pricing may add up
Quick start
curl -X POST https://lowpaymentfee.com/api/v1/carts/53 \
-H "Content-Type: application/json" \
-H "X-PAYMENT: <x402-payment-token>"Endpoint
Quality
The endpoint is live and returns a valid x402 402 challenge, confirming pricing and network. However, there is no OpenAPI spec, no documented request/response schemas, no usage examples, and all documentation pages are empty beyond a wallet-connect prompt. The actual functionality behind '/api/v1/carts/53' is entirely opaque.
Warnings
- —No OpenAPI or schema documentation available — endpoint behavior is unknown beyond the label 'Premium API Access'
- —All doc/pricing/README pages render only 'Connect wallet' with no content
- —The specific endpoint path '/api/v1/carts/53' does not match any of the advertised API paths on the landing page, making its purpose unclear
- —No request body schema or response schema is documented anywhere
Citations
- —Endpoint returns 402 with maxAmountRequired of 20000 base units USDC on Base (scheme: exact, 300s timeout)https://lowpaymentfee.com/api/v1/carts/53
- —Platform advertises $0.02/request pricing with no API keys, no rate limits, and instant access on Base networkhttps://lowpaymentfee.com
- —Available API categories include Data & Analytics, AI & Machine Learning, Finance & Web3, and Infrastructurehttps://lowpaymentfee.com
- —USDC asset address is 0x833589fCD6eDb6E08f4c7C32D4f71b54bdA02913 on Basehttps://lowpaymentfee.com/api/v1/carts/53