x402-gated portfolio transactions endpoint on Base, paid per-call in USDC.
What it does
This endpoint at lowpaymentfee.com provides access to portfolio transaction data via a POST request to `/api/v1/portfolios/20/transactions`. It is part of a broader platform (lowpaymentfee.com) that offers dozens of x402-gated API endpoints spanning data analytics, AI/ML inference, finance/Web3 data, and infrastructure utilities.
The endpoint is live and returns a standard x402 payment challenge. It accepts payment on the Base network in USDC (contract `0x833589fCD6eDb6E08f4c7C32D4f71b54bdA02913`) using the "exact" scheme. The maximum amount required per call is 20,000 base units of USDC, which equals $0.02 (USDC uses 6 decimals). The platform advertises a flat $0.02/request pricing model across all its endpoints, with no API keys, no rate limits, and no minimum commitments.
Documentation is extremely sparse. The docs, API, pricing, and README pages all returned only a "Connect wallet" prompt with no substantive content. There is no OpenAPI schema, no request/response examples, and no description of what fields the transactions endpoint accepts or returns. The endpoint path suggests it retrieves or creates transactions for portfolio ID 20, but the exact input format and response structure are unknown. The platform appears to be a demonstration or early-stage deployment of x402 pay-per-call APIs.
Capabilities
Use cases
- —Fetching or creating portfolio transaction records via a pay-per-call model
- —Integrating x402 payment flows into agent-based financial data pipelines
- —Accessing financial data without API key registration
Fit
Best for
- —Developers experimenting with x402 payment protocol
- —Agents needing keyless, pay-per-call access to portfolio data
- —Low-volume, on-demand transaction data retrieval
Not for
- —High-volume production workloads requiring documented schemas and SLAs
- —Users who need detailed API documentation or response format guarantees
- —Anyone without a Base-network USDC wallet
Quick start
curl -X POST https://lowpaymentfee.com/api/v1/portfolios/20/transactions \
-H "Content-Type: application/json" \
-H "X-PAYMENT: <x402-payment-header>"Endpoint
Quality
The endpoint is live and returns a valid x402 challenge, but there is zero documentation: no OpenAPI schema, no request/response examples, no description of what the endpoint actually does or accepts. Docs pages are all blank 'Connect wallet' stubs. This is effectively a stub listing.
Warnings
- —No API documentation available — all doc pages return only 'Connect wallet' with no content
- —No OpenAPI or input/output schema provided; request and response formats are completely unknown
- —The endpoint path references a specific portfolio ID (20); it is unclear if other portfolio IDs are supported
- —Platform appears to be early-stage or a demo; reliability and data quality are unverified
Citations
- —The endpoint returns a 402 challenge with maxAmountRequired of 20000 base units of USDC on Base networkhttps://lowpaymentfee.com/api/v1/portfolios/20/transactions
- —The platform advertises $0.02/request pricing with no API keys, no rate limits, and instant access on Base networkhttps://lowpaymentfee.com
- —USDC asset contract on Base is 0x833589fCD6eDb6E08f4c7C32D4f71b54bdA02913https://lowpaymentfee.com/api/v1/portfolios/20/transactions