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 resource gated behind the x402 payment protocol. When called without payment, it returns a 402 challenge requesting USDC on the Base network. The specific endpoint `/api/v1/accounts/4/balance` appears to return account balance information in JSON format, accessible via HTTP POST with an x402 payment header.
The parent site lowpaymentfee.com hosts a broader suite of pay-per-request APIs spanning 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 endpoints are listed at $0.02 per request. This specific endpoint's x402 challenge advertises a maxAmountRequired of 20,000 base units of USDC (which has 6 decimals), equating to $0.02 per call — consistent with the site's stated pricing.
Payment settles on the Base L2 network to the USDC contract at 0x833589fCD6eDb6E08f4c7C32D4f71b54bdA02913. No API keys or rate limits are advertised. Documentation pages (/docs, /pricing, /README) returned only a "Connect wallet" prompt with no substantive content, so the actual response schema and detailed behavior of this balance endpoint remain undocumented.
Capabilities
Use cases
- —Querying account balance data via a single paid API call
- —Demonstrating x402 payment protocol integration for agents
- —Programmatic access to balance information without API key management
Fit
Best for
- —Developers experimenting with x402 payment protocol
- —AI agents that can settle micropayments in USDC on Base
- —Use cases requiring keyless, pay-per-request API access
Not for
- —Users needing detailed API documentation or response schemas before integrating
- —High-volume use cases where $0.02/request adds up significantly
- —Users without a Base-compatible USDC wallet
Quick start
curl -X POST https://lowpaymentfee.com/api/v1/accounts/4/balance \
-H "X-PAYMENT: <x402-payment-token>" \
-H "Content-Type: application/json"Endpoint
Quality
The endpoint is live and returns a valid x402 challenge with clear pricing ($0.02 USDC on Base). However, there is no OpenAPI schema, no documented request/response format, and all documentation pages are empty stubs ('Connect wallet'). The purpose of the specific /accounts/4/balance endpoint is unclear beyond its name. This is effectively a stub listing.
Warnings
- —No API documentation available — /docs, /pricing, and /README pages all return only 'Connect wallet' with no content
- —Response schema for this endpoint is completely undocumented; actual returned data structure is unknown
- —The endpoint path includes a hardcoded account ID (4), suggesting it may be a demo or placeholder rather than a general-purpose API
- —The broader site lists many API categories (AI, finance, analytics, etc.) but none of the documentation pages have real content, raising questions about whether these endpoints are fully implemented
Citations
- —The x402 challenge requests 20,000 base units of USDC (0x833589fCD6eDb6E08f4c7C32D4f71b54bdA02913) on Base networkhttps://lowpaymentfee.com/api/v1/accounts/4/balance
- —All endpoints are listed at $0.02 per request with no API keys, no rate limits, and instant accesshttps://lowpaymentfee.com
- —The site advertises APIs across data & analytics, AI & ML, finance & Web3, and infrastructure categorieshttps://lowpaymentfee.com
- —Documentation pages (/docs, /pricing, /README) contain only 'Connect wallet' with no substantive contenthttps://lowpaymentfee.com/docs