x402-gated account balance endpoint on Base, pay-per-call with USDC.
What it does
This endpoint at lowpaymentfee.com provides an account balance lookup via the x402 payment protocol. The specific resource `/api/v1/accounts/9/balance` is gated behind a per-request USDC payment on the Base network. The x402 challenge indicates a maximum cost of 20,000 base units of USDC (0.02 USD per request), consistent with the provider's site-wide $0.02/request pricing model. The endpoint accepts POST requests and returns JSON.
The broader lowpaymentfee.com platform advertises a suite of x402-gated APIs spanning data & analytics, AI/ML (sentiment analysis, summarization, classification, embeddings), finance & Web3 (price feeds, exchange rates, token quotes, gas estimates), and infrastructure utilities (geocoding, validation, conversion, generation). All endpoints share the same $0.02/request pricing with no API keys, no rate limits, and no commitments required — payment is handled entirely via the x402 protocol using USDC on Base.
Documentation is extremely sparse. The docs, API, pricing, 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 detailed description of what the account balance endpoint actually returns or what parameters it accepts. The endpoint is live (returns a valid 402 challenge), but the lack of documentation makes it difficult to assess the actual utility or data quality of the response.
Capabilities
Use cases
- —Querying account balance data via a single paid API call
- —Integrating pay-per-request balance lookups into agent workflows
- —Testing x402 protocol integrations with a low-cost endpoint
Fit
Best for
- —Developers experimenting with x402 payment protocol
- —Agents needing simple pay-per-call API access without API keys
- —Low-volume balance lookups where $0.02/call is acceptable
Not for
- —High-volume balance queries where per-call costs add up
- —Users who need detailed API documentation before integrating
- —Production systems requiring SLA guarantees or support
Quick start
curl -X POST https://lowpaymentfee.com/api/v1/accounts/9/balance \
-H "X-PAYMENT: <x402-payment-token>" \
-H "Content-Type: application/json"Endpoint
Quality
The endpoint is live and returns a valid x402 402 challenge, confirming it is operational. However, documentation is essentially nonexistent — all doc/pricing/API pages show only 'Connect wallet'. There is no OpenAPI schema, no request/response examples, and no description of what the balance endpoint actually returns or what inputs it expects. The specific endpoint path (/api/v1/accounts/9/balance) is not listed among the provider's advertised APIs, raising questions about its intended use.
Warnings
- —No documentation available — all doc pages render only 'Connect wallet'
- —No OpenAPI or JSON schema describing request parameters or response format
- —This specific endpoint (/api/v1/accounts/9/balance) is not listed among the provider's advertised API catalog
- —No examples of request or response payloads available
- —Cannot verify what data the endpoint actually returns
Citations
- —The x402 challenge requires a maximum of 20,000 base units of USDC (USD Coin) on Base network, equivalent to $0.02https://lowpaymentfee.com/api/v1/accounts/9/balance
- —The provider advertises $0.02/request pricing with no API keys, no rate limits, and instant access on Base networkhttps://lowpaymentfee.com
- —The platform offers APIs across data & analytics, AI/ML, finance & Web3, and infrastructure categorieshttps://lowpaymentfee.com