x402-gated API platform on Base offering data, AI, finance, and utility endpoints at $0.02/request.
What it does
lowpaymentfee.com is an x402-protocol API marketplace that gates access to a collection of endpoints behind per-request micropayments settled in USDC on the Base network. The specific endpoint at `/api/v1/inbox/175` is listed as "Premium API Access" and charges up to 20,000 base units of USDC (i.e., $0.02 per request, since USDC uses 6 decimals). No API keys or rate limits are advertised; callers pay per request via the x402 payment header.
The broader platform advertises four categories of endpoints: 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 listed endpoints share the same $0.02/request pricing. However, the specific endpoint `/api/v1/inbox/175` does not clearly map to any of these named categories — it may be a generic or custom inbox endpoint.
Documentation is extremely sparse. The crawled pages beyond the landing page (including /api, /pricing, and /README) returned only a "Connect wallet" prompt with no additional technical detail. There is no OpenAPI spec, no request/response schema documentation, and no usage examples available. The endpoint is confirmed live via a valid 402 challenge, but without documentation it is unclear what payload the POST endpoint expects or what it returns.
Capabilities
Use cases
- —Paying per-request for API access without needing API keys or subscriptions
- —Integrating micropayment-gated endpoints into agent workflows on Base
- —Accessing data, AI inference, finance, or utility services via x402 protocol
Fit
Best for
- —Developers wanting zero-commitment, pay-as-you-go API access
- —AI agents that can settle x402 payments in USDC on Base
- —Projects needing low-cost per-call API access without rate limits
Not for
- —Users who need detailed API documentation or OpenAPI specs before integrating
- —High-volume use cases where per-request pricing may add up compared to subscription models
- —Users without USDC on the Base network
Quick start
curl -X POST https://lowpaymentfee.com/api/v1/inbox/175 \
-H "Content-Type: application/json" \
-H "X-PAYMENT: <x402-payment-token>" \
-d '{}'Endpoint
Quality
The endpoint is confirmed live via a valid x402 402 challenge, and pricing is clear ($0.02/request in USDC on Base). However, there is no OpenAPI spec, no request/response schema, no documentation beyond a landing page listing, and the specific /api/v1/inbox/175 path has no description of its purpose or expected input. This is effectively a stub listing.
Warnings
- —No OpenAPI or schema documentation available for this endpoint
- —The path /api/v1/inbox/175 does not correspond to any of the named endpoints on the landing page — its actual function is unknown
- —All documentation pages (/api, /pricing, /README) returned only 'Connect wallet' with no content
- —No request body schema or response schema is documented anywhere
Citations
- —The endpoint returns a 402 challenge with maxAmountRequired of 20000 base units of USDC on Basehttps://lowpaymentfee.com/api/v1/inbox/175
- —USDC asset contract on Base is 0x833589fCD6eDb6E08f4c7C32D4f71b54bdA02913https://lowpaymentfee.com/api/v1/inbox/175
- —Platform advertises $0.02/request pricing with no API keys, no rate limits, and instant access on Base networkhttps://lowpaymentfee.com
- —Four endpoint categories listed: Data & Analytics, AI & Machine Learning, Finance & Web3, Infrastructurehttps://lowpaymentfee.com