Pay-per-call portfolio holdings API on Base network via x402 protocol, settled in USDC.
What it does
This endpoint at lowpaymentfee.com provides access to portfolio holdings data (portfolio ID 25) via the x402 payment protocol. It accepts POST requests and returns JSON responses. Payment is settled on the Base network using USDC (contract 0x833589fCD6eDb6E08f4c7C32D4f71b54bdA02913) with a maximum cost of $0.02 per request (20000 base units at 6 decimals).
The endpoint is part of a broader platform (lowpaymentfee.com) that offers various pay-per-call APIs spanning data analytics, AI/ML inference, finance/Web3 data, and utility services—all priced at $0.02 per request with no API keys, no rate limits, and no minimum commitments. The x402 protocol enables direct machine-to-machine payments: callers include an X-PAYMENT header with a signed payment proof, and the server validates it before returning data.
The specific data returned by this holdings endpoint is not documented in detail. Based on the URL structure (`/portfolios/25/holdings`), it likely returns a list of asset holdings for a particular portfolio, but the exact schema of the response is not provided in available documentation. The platform's docs, pricing, and README pages all require wallet connection and do not expose further technical details publicly.
Capabilities
Use cases
- —Retrieving portfolio asset holdings programmatically without API key registration
- —Agent-driven portfolio monitoring with per-call USDC micropayments
- —Integrating holdings data into automated trading or rebalancing workflows
Fit
Best for
- —AI agents needing on-demand portfolio data without subscription
- —Developers wanting frictionless pay-per-use financial data access
- —Applications that settle payments on Base L2 in USDC
Not for
- —Users who need free or subscription-based bulk data access
- —Applications requiring detailed API documentation or guaranteed SLAs
- —Non-crypto-native clients who cannot produce x402 payment headers
Quick start
curl -X POST https://lowpaymentfee.com/api/v1/portfolios/25/holdings \
-H "Content-Type: application/json" \
-H "X-PAYMENT: <signed_x402_payment_proof>"Endpoint
Quality
The endpoint is live (402 challenge confirmed) and pricing is clear, but there is no documentation of request parameters, response schema, or what data portfolio 25 actually contains. The docs pages require wallet connection and reveal nothing.
Warnings
- —No response schema or example response documented
- —No request body schema documented—unclear what parameters (if any) the POST body accepts
- —Portfolio ID 25 is hardcoded in the URL with no explanation of what it represents
- —Platform docs/pricing/README pages all gate content behind wallet connection, providing no public documentation
Citations
- —Endpoint returns 402 with x402 challenge requiring USDC payment on Base networkhttps://lowpaymentfee.com/api/v1/portfolios/25/holdings
- —Platform advertises $0.02 per request pricing with no API keys, no rate limitshttps://lowpaymentfee.com
- —USDC asset contract is 0x833589fCD6eDb6E08f4c7C32D4f71b54bdA02913https://lowpaymentfee.com/api/v1/portfolios/25/holdings