x402-gated premium API access on Base, pay $0.02 per request in USDC.
What it does
This endpoint at lowpaymentfee.com provides "Premium API Access" via the x402 payment protocol on the Base network. The endpoint is live and returns a standard 402 challenge requiring payment in USDC (contract 0x8335…2913 on Base) with a maximum amount of 20,000 base units, which equals $0.02 per request (USDC uses 6 decimals). Payment is settled on-chain with no API keys, no rate limits, and no commitments required.
The specific endpoint `/api/v1/charges/163` is labeled "Premium API Access" in the x402 challenge but the crawl material does not clarify what data or functionality this particular charge ID returns. The broader lowpaymentfee.com platform advertises multiple API categories — data & analytics, AI & machine learning (sentiment analysis, summarization, classification, embeddings), finance & Web3 (price feeds, exchange rates, token quotes, gas estimates), and infrastructure utilities (geocoding, validation, conversion, generation) — all priced at $0.02 per request. However, the `/api/v1/charges/163` path does not directly map to any of the listed endpoints, so its exact functionality is unclear.
The x402 challenge specifies the input method as HTTP POST, the response MIME type as application/json, and a maximum timeout of 300 seconds. No OpenAPI schema, detailed documentation, or example request/response bodies were found in the crawl. The docs, API, pricing, and README pages all returned only a "Connect wallet" prompt with no substantive content.
Capabilities
Use cases
- —Paying per-request for API access without needing API keys or subscriptions
- —Agent-driven programmatic access to premium endpoints via x402 protocol
- —On-chain micropayment-gated API consumption on Base
Fit
Best for
- —Developers wanting keyless, pay-per-use API access
- —AI agents that can settle x402 payments autonomously
- —Users who prefer on-chain USDC micropayments over traditional billing
Not for
- —Users needing detailed documentation or OpenAPI specs before integrating
- —Anyone requiring free or subscription-based access without crypto payments
- —Use cases requiring guaranteed SLAs or documented rate limits
Quick start
curl -X POST https://lowpaymentfee.com/api/v1/charges/163 \
-H "Content-Type: application/json"
# Returns 402 with x402 challenge; attach X-PAYMENT header with valid payment to access.Example
Response
{
"error": "X-PAYMENT header is required",
"accepts": [
{
"asset": "0x833589fCD6eDb6E08f4c7C32D4f71b54bdA02913",
"extra": {
"name": "USD Coin",
"version": "2"
},
"payTo": "0x1A2B13E97f5F837C8F9FA1F95a1484B7C70d85F3",
"scheme": "exact",
"network": "base",
"mimeType": "application/json",
"resource": "https://lowpaymentfee.com/api/v1/charges/163",
"description": "Premium API Access",
"maxAmountRequired": "20000",
"maxTimeoutSeconds": 300
}
],
"x402Version": 1
}Endpoint
Quality
The endpoint is live and returns a valid x402 challenge with clear pricing ($0.02 USDC on Base). However, there is no documentation, no OpenAPI schema, no example request/response for the actual paid resource, and the specific functionality behind /api/v1/charges/163 is not described anywhere in the crawl material. The docs pages are empty beyond a wallet-connect prompt.
Warnings
- —The specific functionality of /api/v1/charges/163 ('Premium API Access') is not documented — it does not map to any of the named endpoints listed on the homepage.
- —No OpenAPI spec, request schema, or response schema is available.
- —All documentation pages (docs, API, pricing, README) returned only a 'Connect wallet' prompt with no substantive content.
- —The actual paid response content is unknown without making a payment.
Citations
- —Endpoint returns 402 with x402 challenge requiring USDC payment on Base networkhttps://lowpaymentfee.com/api/v1/charges/163
- —Platform advertises $0.02 per request pricing with no API keys, no rate limits, and instant accesshttps://lowpaymentfee.com
- —USDC asset contract on Base is 0x833589fCD6eDb6E08f4c7C32D4f71b54bdA02913https://lowpaymentfee.com/api/v1/charges/163
- —Platform lists multiple API categories including AI, finance, data analytics, and infrastructurehttps://lowpaymentfee.com