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/21/transactions`. It is part of a broader platform offering data & analytics, AI/ML inference, finance/Web3, and infrastructure utility APIs, all priced at $0.02 per request with no API keys, no rate limits, and no commitments required.
Payment is settled on the Base network using USDC (contract `0x833589fCD6eDb6E08f4c7C32D4f71b54bdA02913`). The x402 challenge specifies a `maxAmountRequired` of 20,000 base units, which at 6 decimals equals $0.02 USD per call. The endpoint uses the "exact" payment scheme with a 300-second timeout. No OpenAPI schema or detailed documentation was found for this specific endpoint beyond the x402 challenge metadata.
The specific endpoint listed here (`/api/v1/portfolios/21/transactions`) appears to be a portfolio-specific transactions resource, likely returning or accepting transaction records for portfolio ID 21. However, the request and response schemas are not documented, so the exact input format and output structure are unknown. The broader platform advertises categories including finance, crypto, AI, and utility endpoints, all following the same x402 payment pattern.
Capabilities
Use cases
- —Retrieving or submitting transaction records for a specific portfolio
- —Integrating portfolio transaction data into automated trading or analytics pipelines
- —Agent-driven portfolio management workflows that pay per API call with USDC
Fit
Best for
- —Developers wanting keyless, pay-per-call access to portfolio transaction data
- —AI agents that can settle x402 payments on Base with USDC
- —Projects needing low-cost API access without subscription commitments
Not for
- —Users who need detailed API documentation or OpenAPI specs before integrating
- —High-volume use cases where $0.02/request adds up significantly
- —Users without USDC on the Base network
Quick start
curl -X POST https://lowpaymentfee.com/api/v1/portfolios/21/transactions \
-H "Content-Type: application/json" \
-H "X-PAYMENT: <x402-payment-header>"Endpoint
Quality
The endpoint is live and returns a valid x402 challenge with clear pricing, but there is no OpenAPI schema, no request/response documentation, and the crawled docs/pricing/API pages are all empty (just 'Connect wallet'). The purpose of this specific endpoint (portfolios/21/transactions) is unclear beyond the generic 'Premium API Access' label.
Warnings
- —No OpenAPI or request/response schema available for this endpoint
- —Documentation pages (/docs, /api, /pricing, /README) returned no useful content
- —The endpoint path references a hardcoded portfolio ID (21), which may not be generalizable
- —Exact input format and response structure are unknown
Citations
- —The x402 challenge specifies maxAmountRequired of 20000 base units in USDC on Base networkhttps://lowpaymentfee.com/api/v1/portfolios/21/transactions
- —All APIs on the platform are priced at $0.02 per request with no API keys, no rate limits, and instant accesshttps://lowpaymentfee.com
- —USDC asset contract is 0x833589fCD6eDb6E08f4c7C32D4f71b54bdA02913https://lowpaymentfee.com/api/v1/portfolios/21/transactions