Premium API access via x402 micropayment on Base — $0.02 per request in USDC.
What it does
lowpaymentfee.com is an x402-enabled API marketplace offering a broad set of endpoints across data analytics, AI/ML inference, finance/Web3, and infrastructure utilities. Every endpoint is priced at $0.02 per request, paid in USDC on the Base network with no API keys, no rate limits, and no upfront commitments. The platform uses the x402 payment protocol: callers receive a 402 challenge containing payment details, settle in USDC on-chain, and then receive the API response.
The specific endpoint at `/api/v1/apikeys/99` is listed as "Premium API Access." Its 402 challenge advertises a maxAmountRequired of 20,000 base units of USDC (0x8335… on Base), which equals $0.02 given USDC's 6 decimals. The payment is sent to address 0x1A2B13E97f5F837C8F9FA1F95a1484B7C70d85F3 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 — all at the same $0.02 price point. Documentation pages (docs, pricing, README) were largely empty during crawl, returning only a "Connect wallet" prompt, so detailed request/response schemas are unavailable.
Capabilities
Use cases
- —Agent-driven API consumption with per-call USDC micropayments on Base
- —Accessing AI inference endpoints (sentiment, summarization, classification, embeddings) without API keys
- —Fetching real-time crypto price feeds, gas estimates, and exchange rates on demand
- —Geocoding, data validation, and utility conversions via pay-per-use endpoints
Fit
Best for
- —Developers and AI agents wanting zero-signup, pay-per-request API access
- —Web3-native applications that can settle USDC on Base
- —Low-volume or bursty workloads where subscription pricing is wasteful
Not for
- —High-volume production workloads needing guaranteed SLAs and detailed documentation
- —Users without a Base-compatible wallet or USDC holdings
- —Applications requiring detailed OpenAPI schemas and request/response contracts upfront
Quick start
curl -X POST https://lowpaymentfee.com/api/v1/apikeys/99 \
-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, documentation pages are effectively empty, there is no OpenAPI schema, no request/response examples, and the purpose of the specific /api/v1/apikeys/99 endpoint (vs. the many other listed endpoints) is unclear. The listing is functional but sparse.
Warnings
- —Documentation pages (/docs, /pricing, /README) returned only 'Connect wallet' with no actual content during crawl.
- —No OpenAPI or request/response schema is available for any endpoint.
- —The specific purpose of /api/v1/apikeys/99 ('Premium API Access') is unclear — it may be a meta-endpoint for generating API keys rather than a data endpoint.
- —The broader platform lists many endpoints but none were individually probed for liveness beyond this one.
Citations
- —Endpoint returns 402 with x402 challenge advertising maxAmountRequired of 20000 base units USDC on Basehttps://lowpaymentfee.com/api/v1/apikeys/99
- —Platform lists endpoints across Data & Analytics, AI & ML, Finance & Web3, and Infrastructure categories all at $0.02 per requesthttps://lowpaymentfee.com
- —Pricing is $0.02 per request with no API keys, no rate limits, instant access on Base networkhttps://lowpaymentfee.com
- —USDC asset address is 0x833589fCD6eDb6E08f4c7C32D4f71b54bdA02913 on Basehttps://lowpaymentfee.com/api/v1/apikeys/99