Pay-per-call API key generation on Base via x402 — $0.02 per request in USDC.
What it does
lowpaymentfee.com is an x402-enabled API platform that offers a variety of endpoints across data & analytics, AI & machine learning, finance & Web3, and infrastructure utilities. All endpoints are priced at $0.02 per request, payable in USDC on the Base network with no API keys, rate limits, or commitments required.
The specific endpoint at `/api/v1/apikeys/100` is described as "Premium API Access" and returns an 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 settled on-chain to address 0x1A2B13E97f5F837C8F9FA1F95a1484B7C70d85F3 using the "exact" scheme with a 300-second timeout. The endpoint accepts POST requests.
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 per-call 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. There is no OpenAPI spec, no request/response schema documentation, and no usage examples available from the crawled material. The actual functionality behind each endpoint is unclear.
Capabilities
Use cases
- —Acquiring API access credentials via a single on-chain micropayment
- —Programmatic pay-per-use access to data, AI, finance, and utility endpoints
- —Agent-driven API consumption without pre-registration or API key management
Fit
Best for
- —Developers wanting zero-signup, pay-as-you-go API access
- —AI agents that can settle x402 payments autonomously on Base
- —Users who prefer on-chain USDC micropayments over subscription billing
Not for
- —Users needing detailed API documentation or OpenAPI specs before purchasing
- —High-volume consumers who need bulk pricing or SLAs
- —Anyone without a Base-compatible USDC wallet
Quick start
curl -X POST https://lowpaymentfee.com/api/v1/apikeys/100 \
-H "Content-Type: application/json" \
-H "X-PAYMENT: <x402-payment-header>"Endpoint
Quality
The endpoint is live and returns a valid x402 challenge with clear pricing. However, there is no OpenAPI spec, no request/response schema, and all documentation pages beyond the landing page are empty ('Connect wallet' only). The actual functionality behind 'Premium API Access' and the other listed endpoints is undocumented and unverifiable.
Warnings
- —No OpenAPI or schema documentation available — endpoint behavior is unknown beyond the x402 challenge
- —All doc/pricing/API/README pages render only 'Connect wallet' with no content
- —The specific purpose of /api/v1/apikeys/100 ('Premium API Access') is not explained anywhere
- —Cannot verify that the advertised AI, finance, data, and utility endpoints actually function as described
Citations
- —The endpoint returns an x402 challenge requesting up to 20,000 base units of USDC on Base ($0.02)https://lowpaymentfee.com/api/v1/apikeys/100
- —All endpoints are priced at $0.02 per request with no API keys, rate limits, or commitmentshttps://lowpaymentfee.com
- —The platform advertises endpoints across Data & Analytics, AI & ML, Finance & Web3, and Infrastructure categorieshttps://lowpaymentfee.com
- —USDC asset contract on Base is 0x833589fCD6eDb6E08f4c7C32D4f71b54bdA02913https://lowpaymentfee.com/api/v1/apikeys/100