x402-gated account balance endpoint on Base, paid per-call in USDC.
What it does
This endpoint at lowpaymentfee.com exposes an account balance lookup at `/api/v1/accounts/40/balance`. It is part of a broader platform that advertises multiple API categories including data & analytics, AI & machine learning, finance & Web3, and infrastructure utilities — all gated behind x402 micropayments on the Base network using USDC.
The specific endpoint probed returns an x402 challenge requesting up to $0.02 per call (maxAmountRequired of 20,000 base units of USDC, which has 6 decimals = $0.02). Payment is settled on-chain via the "exact" scheme to a specified wallet address. The endpoint accepts POST requests and returns `application/json`. No API keys or rate limits are advertised; access is granted purely through per-request x402 payment.
Documentation is extremely sparse. The landing page lists available endpoints and pricing, but the /docs, /pricing, /api, and /README pages all render only a "Connect wallet" prompt with no substantive content. There is no OpenAPI schema, no request/response examples, and no description of what the "balance" endpoint actually returns or what parameters it accepts. The endpoint is live (402 challenge confirmed), but the lack of documentation makes it difficult to use without experimentation.
Capabilities
Use cases
- —Querying account balance data via a pay-per-request model
- —Integrating micropayment-gated API calls into agent workflows
- —Accessing financial data without API key registration
Fit
Best for
- —Developers wanting keyless, pay-per-call API access
- —AI agents with x402-compatible payment capabilities
- —Users who prefer on-chain USDC micropayments over subscriptions
Not for
- —Users needing detailed API documentation or schemas before integration
- —High-volume consumers who need bulk pricing or rate-limit guarantees
- —Anyone without a Base-network USDC wallet
Quick start
curl -X POST https://lowpaymentfee.com/api/v1/accounts/40/balance \
-H "Content-Type: application/json" \
-H "X-PAYMENT: <x402-payment-token>"Endpoint
Quality
The endpoint is live and returns a valid x402 challenge with clear pricing, but there is essentially no documentation: no OpenAPI schema, no request/response examples, and the docs/pricing/README pages are all empty wallet-connect stubs. The purpose of this specific 'accounts/40/balance' endpoint is unclear beyond its name.
Warnings
- —No OpenAPI or request/response schema available — endpoint behavior must be discovered experimentally
- —All documentation pages (/docs, /pricing, /api, /README) render only 'Connect wallet' with no content
- —The specific meaning of 'accounts/40/balance' (what account 40 is, what balance is returned) is undocumented
- —No information on error handling, response format, or required request body fields
Citations
- —The endpoint returns an x402 challenge with maxAmountRequired of 20000 base units of USDC on Base networkhttps://lowpaymentfee.com/api/v1/accounts/40/balance
- —The platform advertises $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/40/balance