x402-gated portfolio transactions endpoint on Base, pay $0.02 per request in USDC.
What it does
This endpoint at lowpaymentfee.com provides access to portfolio transaction data via a POST request to `/api/v1/portfolios/43/transactions`. It is part of a broader platform (lowpaymentfee.com) that offers a variety of x402-payable APIs spanning data analytics, AI/ML inference, finance/Web3 data, and infrastructure utilities — all priced at $0.02 per request.
The specific endpoint probed here returns an x402 challenge requesting payment of up to 20,000 base units of USDC (0x8335…2913 on Base network), which equals $0.02 USD (USDC uses 6 decimals). Payment is settled on the Base L2 network using the x402 "exact" scheme. No API keys or rate limits are advertised; access is granted per-request upon valid payment.
Documentation on the site 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 schema, no request/response examples, and no description of what the portfolio transactions endpoint actually returns or what parameters it accepts. The endpoint is live (402 challenge confirmed), but without documentation it is difficult to know the expected POST body or the shape of the response.
Capabilities
Use cases
- —Fetching portfolio transaction records behind a per-request paywall
- —Integrating pay-per-call financial data into agent workflows
- —Accessing transaction data without API key registration
Fit
Best for
- —Agents that can settle x402 payments in USDC on Base
- —Developers wanting keyless, pay-per-use portfolio data access
- —Automated workflows needing on-demand transaction retrieval
Not for
- —Users who need detailed API documentation or schemas before integrating
- —High-volume consumers who need bulk/subscription pricing
- —Anyone unable to pay with USDC on Base network
Quick start
curl -X POST https://lowpaymentfee.com/api/v1/portfolios/43/transactions \
-H "Content-Type: application/json" \
-H "X-PAYMENT: <x402-payment-token>" \
-d '{}'Endpoint
Quality
The endpoint is live and returns a valid x402 challenge, but there is virtually no documentation: no OpenAPI spec, no request/response schema, no description of what portfolio 43 represents, and all doc pages render only 'Connect wallet'. The listing is effectively a stub.
Warnings
- —No API documentation available — docs, pricing, API, and README pages all show only 'Connect wallet'
- —No OpenAPI or request/response schema provided; request body and response format are unknown
- —The specific resource '/api/v1/portfolios/43/transactions' is not listed on the site's landing page among advertised APIs
- —Purpose of 'portfolio 43' is unexplained; may be a demo or placeholder
Citations
- —The endpoint returns an x402 challenge with maxAmountRequired of 20000 base units of USDC on Base networkhttps://lowpaymentfee.com/api/v1/portfolios/43/transactions
- —The platform advertises $0.02 per request pricing with no API keys, no rate limits, and instant access on Base networkhttps://lowpaymentfee.com
- —The USDC asset contract on Base is 0x833589fCD6eDb6E08f4c7C32D4f71b54bdA02913https://lowpaymentfee.com/api/v1/portfolios/43/transactions