x402-gated account balance endpoint on Base, pay-per-call with USDC.
What it does
This endpoint at lowpaymentfee.com provides a "Premium API Access" account balance lookup via the x402 payment protocol. It is part of a broader platform that advertises multiple API categories including data & analytics, AI & machine learning, finance & Web3, and infrastructure utilities — all priced at $0.02 per request and settled in USDC on the Base network.
The specific endpoint `/api/v1/accounts/99/balance` accepts POST requests and returns JSON. Payment is handled inline via the x402 protocol: callers must include an `X-PAYMENT` header with a valid payment proof. The x402 challenge confirms the endpoint is live, advertising a max amount of 20,000 base units of USDC (0x8335…2913 on Base), which equals $0.02 given USDC's 6 decimals. The payment is sent to address `0x1A2B13E97f5F837C8F9FA1F95a1484B7C70d85F3` with a 300-second timeout.
Documentation is extremely sparse — the docs, pricing, API, 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 explanation of what "accounts/99/balance" actually returns or what input parameters it expects. The platform's landing page lists many endpoints across several categories, but none of them have documented schemas or example payloads. Use with caution: the actual behavior behind this endpoint is opaque.
Capabilities
Use cases
- —Querying account balance data via a pay-per-call model without API keys
- —Demonstrating x402 protocol integration for agent-to-service payments
- —Accessing financial account information settled in USDC on Base
Fit
Best for
- —Developers experimenting with x402 payment protocol
- —Agents that need keyless, pay-per-request API access
- —Use cases requiring low-cost ($0.02) per-call pricing with no subscriptions
Not for
- —Production workloads requiring documented request/response schemas
- —Users who need detailed API documentation or support
- —High-volume use cases where per-request pricing may add up
Quick start
curl -X POST https://lowpaymentfee.com/api/v1/accounts/99/balance \
-H "Content-Type: application/json" \
-H "X-PAYMENT: <x402-payment-proof>"Endpoint
Quality
The endpoint is live (402 challenge captured) and pricing is clear ($0.02 USDC on Base), but there is zero documentation on request parameters, response schema, or what the endpoint actually does beyond the generic label "Premium API Access". No OpenAPI spec, no examples, and all doc pages are empty.
Warnings
- —No API documentation available — docs, pricing, API, and README pages all show only 'Connect wallet'
- —No request or response schema provided; endpoint behavior is opaque
- —The endpoint path '/api/v1/accounts/99/balance' suggests a hardcoded account ID (99) with no explanation of parameterization
- —The platform lists many endpoints across categories but none appear to have documented schemas
Citations
- —The endpoint returns a 402 challenge with maxAmountRequired of 20000 base units of USDC on Base networkhttps://lowpaymentfee.com/api/v1/accounts/99/balance
- —All endpoints on the platform are priced at $0.02 per request with no API keys, no rate limits, and instant accesshttps://lowpaymentfee.com
- —USDC asset contract on Base is 0x833589fCD6eDb6E08f4c7C32D4f71b54bdA02913https://lowpaymentfee.com/api/v1/accounts/99/balance
- —Payment recipient address is 0x1A2B13E97f5F837C8F9FA1F95a1484B7C70d85F3https://lowpaymentfee.com/api/v1/accounts/99/balance