Premium API access via x402 micropayment on Base — $0.02 per request in USDC.
What it does
This endpoint at lowpaymentfee.com provides "Premium API Access" gated behind the x402 payment protocol. The site hosts a broad catalog of pay-per-call APIs spanning 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.
The specific endpoint `/api/v1/apikeys/25` is described only as "Premium API Access" and returns a live x402 402 challenge with a maxAmountRequired of 20,000 base units of USDC (0x8335…2913 on Base), which equals $0.02. Payment is made via the x402 exact scheme — callers attach an X-PAYMENT header with a signed payment to the payTo address. There are no API keys, no rate limits, and no signup required; access is instant once payment is included.
Documentation is extremely sparse. The /docs, /api, /pricing, and /README pages all render only a "Connect wallet" prompt with no further content. There is no OpenAPI spec, no request/response schema, and no examples available. The purpose of the `/api/v1/apikeys/25` path specifically (as opposed to the other listed endpoints) is unclear — it may generate or retrieve an API key, but this is unconfirmed. Prospective callers should be aware that without documented input/output schemas, integration requires experimentation.
Capabilities
Use cases
- —Acquiring API keys or premium access tokens via a single micropayment
- —Programmatic agents purchasing API credentials without signup or subscription
- —Demonstrating x402 payment-gated API access on Base
Fit
Best for
- —Agents or developers wanting instant, keyless API access via crypto micropayment
- —x402-compatible wallets and agent frameworks on Base
- —Low-friction pay-per-use API consumption without accounts
Not for
- —Users who need detailed API documentation or OpenAPI specs before integrating
- —High-volume consumers who prefer subscription-based pricing over per-call payments
- —Non-crypto users without a Base-compatible wallet
Quick start
curl -X POST https://lowpaymentfee.com/api/v1/apikeys/25 \
-H "Content-Type: application/json" \
-H "X-PAYMENT: <x402-signed-payment>"Endpoint
Quality
The endpoint is live and returns a valid x402 402 challenge, confirming it is operational. However, there is no OpenAPI spec, no documented request/response schema, no examples, and the docs pages are empty. The specific purpose of /api/v1/apikeys/25 is unclear beyond the generic 'Premium API Access' label.
Warnings
- —No OpenAPI or schema documentation available — all docs pages render only 'Connect wallet'
- —The specific function of /api/v1/apikeys/25 is undocumented; 'Premium API Access' is vague
- —No request body schema or response schema is provided; integration requires trial and error
- —The site lists many other endpoints but none have documented schemas either
Citations
- —The endpoint returns a live x402 402 challenge with maxAmountRequired of 20000 base units of USDC on Basehttps://lowpaymentfee.com/api/v1/apikeys/25
- —All endpoints are priced at $0.02 per request with no API keys, no rate limits, and instant access on Base networkhttps://lowpaymentfee.com
- —The USDC asset contract on Base is 0x833589fCD6eDb6E08f4c7C32D4f71b54bdA02913https://lowpaymentfee.com/api/v1/apikeys/25
- —Docs, API, pricing, and README pages render only a 'Connect wallet' prompthttps://lowpaymentfee.com/docs