Pay-per-call portfolio transactions endpoint on Base via x402 (USDC, $0.02/request).
What it does
This x402-enabled endpoint at lowpaymentfee.com provides access to portfolio transaction data via a POST request to `/api/v1/portfolios/5/transactions`. It is part of a broader platform offering dozens of pay-per-call APIs spanning data analytics, AI/ML inference, finance/Web3 data, and infrastructure utilities — all priced at $0.02 per request and settled in USDC on the Base network.
The endpoint uses the x402 payment protocol (version 1, "exact" scheme). Callers must include an `X-PAYMENT` header containing a valid payment proof. The maximum amount required per call is 20,000 base units of USDC (0x8335…2913 on Base), which equals $0.02 given USDC's 6 decimals. Payment is sent to address `0x1A2B13E97f5F837C8F9FA1F95a1484B7C70d85F3` with a 300-second timeout window. The response MIME type is `application/json`.
Documentation on the site is extremely thin — 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 fields the transactions endpoint accepts or returns. The endpoint name suggests it retrieves or creates transactions for a specific portfolio (ID 5), but the exact semantics (read vs. write, required body fields, response shape) are unknown from available materials.
Capabilities
Use cases
- —Retrieving or submitting portfolio transaction records via a single paid API call
- —Integrating pay-per-use financial data into agent workflows without API key management
- —Programmatic access to portfolio data settled on-chain via USDC on Base
Fit
Best for
- —Agents or developers wanting keyless, pay-per-call access to portfolio transaction data
- —x402-compatible clients that can construct USDC payment proofs on Base
- —Low-volume or sporadic usage where $0.02/request flat pricing is attractive
Not for
- —Users who need detailed API documentation or schema validation before integrating
- —High-volume bulk data retrieval where per-request pricing would be costly
- —Anyone without a Base-network USDC wallet or x402-compatible payment client
Quick start
curl -X POST https://lowpaymentfee.com/api/v1/portfolios/5/transactions \
-H "Content-Type: application/json" \
-H "X-PAYMENT: <x402-payment-proof>" \
-d '{}'Endpoint
Quality
The endpoint is live (402 challenge confirmed) and pricing is clear ($0.02 USDC on Base), but there is zero documentation on request/response schemas, no OpenAPI spec, and all doc pages render only 'Connect wallet'. The specific endpoint path (/portfolios/5) is hardcoded to a single portfolio ID with no explanation. Effectively a stub listing.
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 completely unknown
- —The endpoint path is hardcoded to portfolio ID 5 with no explanation of what this portfolio represents
- —Cannot verify what data is actually returned or what POST body fields are accepted
Citations
- —The endpoint returns a 402 challenge with maxAmountRequired of 20000 base units of USDC on Basehttps://lowpaymentfee.com/api/v1/portfolios/5/transactions
- —All APIs on the platform are priced at $0.02 per request with no API keys, no rate limits, and instant access on the Base networkhttps://lowpaymentfee.com
- —The USDC asset contract on Base is 0x833589fCD6eDb6E08f4c7C32D4f71b54bdA02913https://lowpaymentfee.com/api/v1/portfolios/5/transactions