x402-gated account balance endpoint on Base, pay-per-call with USDC.
What it does
This endpoint at lowpaymentfee.com provides a pay-per-request "Premium API Access" resource at the path `/api/v1/accounts/20/balance`. It is part of a broader platform that offers multiple API categories including data & analytics, AI & machine learning, finance & Web3, and infrastructure utilities — all gated behind x402 micropayments settled in USDC on the Base network.
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). Payment is made via the x402 "exact" scheme to the specified payTo 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 payment.
Documentation on the site is extremely sparse — the docs, pricing, API, and README pages all render only a "Connect wallet" prompt with no substantive content. There is no OpenAPI spec, no request/response schema documentation, and no examples of what the balance endpoint actually returns. The endpoint name suggests it retrieves an account balance (account ID 20), but the exact semantics, required request body, and response format are unknown. The platform lists a uniform $0.02/request pricing across all its endpoints.
Capabilities
Use cases
- —Querying account balance data via a single micropayment without API key registration
- —Integrating pay-per-call balance lookups into autonomous agent workflows
- —Testing x402 protocol payment flows on Base network
Fit
Best for
- —Developers experimenting with x402 payment protocol
- —Agents needing keyless, pay-per-request API access on Base
- —Low-volume balance queries without subscription commitments
Not for
- —Production workloads requiring documented request/response schemas
- —High-volume use cases where per-request pricing is inefficient
- —Users who need detailed API documentation before integration
Quick start
# 1. Send a POST to get the x402 challenge
curl -X POST https://lowpaymentfee.com/api/v1/accounts/20/balance
# Returns 402 with x402 payment challenge
# 2. Construct X-PAYMENT header with USDC payment proof on Base
# 3. Resend POST with X-PAYMENT header to receive the balance responseEndpoint
Quality
The endpoint is live and returns a valid x402 challenge, but there is no documentation, no OpenAPI spec, no request/response schema, and no examples. The docs pages are empty stubs. The purpose of this specific endpoint (account 20 balance) is unclear beyond the URL path. This is effectively a stub listing.
Warnings
- —No API documentation available — docs, pricing, API, and README pages all show only 'Connect wallet' with no content
- —No OpenAPI or schema definition for request body or response format
- —The specific semantics of 'accounts/20/balance' are undocumented — unclear what account 20 refers to
- —No examples of successful responses available anywhere in crawled content
- —Platform appears to be a demo or early-stage project with many listed endpoints but no substantive documentation
Citations
- —The endpoint returns a 402 x402 challenge with maxAmountRequired of 20000 base units of USDC on Base networkhttps://lowpaymentfee.com/api/v1/accounts/20/balance
- —The platform advertises $0.02/request pricing with no API keys, no rate limits, and instant access on Base networkhttps://lowpaymentfee.com
- —USDC asset address 0x833589fCD6eDb6E08f4c7C32D4f71b54bdA02913 on Basehttps://lowpaymentfee.com/api/v1/accounts/20/balance
- —Docs, pricing, API, and README pages render only 'Connect wallet' with no documentation contenthttps://lowpaymentfee.com/docs