Pay-per-call API platform on Base (USDC) offering data, AI, finance, and utility endpoints at $0.02/request.
What it does
lowpaymentfee.com is an x402-enabled API platform that provides a broad suite of endpoints across four categories: Data & Analytics (metrics, reports, data export, insights), AI & Machine Learning (sentiment analysis, text summarization, classification, embeddings), Finance & Web3 (price feeds, exchange rates, token quotes, gas estimates), and Infrastructure utilities (geocoding, validation, conversion, generation). All endpoints are priced at $0.02 per request, settled in USDC on the Base network via the x402 protocol.
The specific endpoint `/api/v1/keys/2` is listed as "Premium API Access" and returns a 402 challenge requesting up to 20,000 base units of USDC (0.02 USD, since USDC uses 6 decimals) on Base. Payment is made via the x402 exact scheme with no API keys, no rate limits, and no subscriptions required — callers simply attach an X-PAYMENT header to each request. The endpoint accepts POST requests and returns application/json responses.
Documentation beyond the landing page is sparse: the /api, /pricing, and /README pages all resolve to a "Connect wallet" prompt with no additional technical detail. There is no OpenAPI spec, no request/response schema documentation, and no usage examples available from the crawled material. The exact functionality behind the "Premium API Access" label at `/api/v1/keys/2` is unclear — it may provide an API key or elevated access, but this is not documented.
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 data analytics queries and exporting data with no subscription commitment
- —Geocoding, validation, and conversion utilities paid per request via USDC on Base
Fit
Best for
- —Developers who want zero-commitment, pay-as-you-go API access
- —AI agents that can autonomously pay for API calls via x402
- —Projects already operating on the Base network with USDC
Not for
- —Users needing detailed API documentation or OpenAPI specs before integrating
- —High-volume consumers who would benefit from bulk pricing or rate-limited tiers
- —Anyone without a Base-compatible USDC wallet
Quick start
curl -X POST https://lowpaymentfee.com/api/v1/keys/2 \
-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, there is no OpenAPI spec, no request/response schema, no usage examples, and the specific purpose of /api/v1/keys/2 ('Premium API Access') is undocumented. Most site pages beyond the landing page are empty wallet-connect prompts.
Warnings
- —No OpenAPI or schema documentation available for any endpoint
- —The exact purpose and response format of /api/v1/keys/2 is unclear — 'Premium API Access' is not explained
- —All non-landing pages (/api, /pricing, /README) returned only a 'Connect wallet' prompt with no content
- —No request body schema or response examples are documented anywhere in the crawled material
Citations
- —The endpoint returns a 402 challenge requesting up to 20,000 base units of USDC on Base (0.02 USD)https://lowpaymentfee.com/api/v1/keys/2
- —All listed endpoints are priced at $0.02 per request with no API keys, no rate limits, and instant accesshttps://lowpaymentfee.com
- —The platform offers endpoints across Data & Analytics, AI & ML, Finance & Web3, and Infrastructure categorieshttps://lowpaymentfee.com
- —USDC asset address 0x833589fCD6eDb6E08f4c7C32D4f71b54bdA02913 on Base networkhttps://lowpaymentfee.com/api/v1/keys/2