Pay-per-call portfolio transactions endpoint on Base via x402, settled in USDC.
What it does
This x402-enabled endpoint at lowpaymentfee.com provides access to portfolio transaction data at `/api/v1/portfolios/85/transactions`. It accepts POST requests and is gated by an x402 payment challenge, settling on the Base network in USDC. The maximum amount required per call is 20,000 base units of USDC (6 decimals), which equals $0.02 per request.
The endpoint is part of a broader platform (lowpaymentfee.com) that offers a variety of pay-per-call APIs spanning data & analytics, AI & machine learning, finance & Web3, and infrastructure utilities — all priced at $0.02 per request. The platform advertises no API keys, no rate limits, and instant access. Payment is handled entirely through the x402 protocol using USDC on the Base L2 network.
Documentation for this specific endpoint is extremely sparse. The crawled docs, API, pricing, and README pages all returned 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 is confirmed live (returns a valid 402 challenge), but the actual functionality behind the paywall is unknown beyond the generic "Premium API Access" label.
Capabilities
Use cases
- —Retrieving transaction records for a specific portfolio
- —Integrating portfolio transaction data into automated trading or analytics pipelines
- —Agent-driven portfolio monitoring with per-call micropayments
Fit
Best for
- —Developers needing pay-per-call portfolio transaction data without API key management
- —AI agents that can settle x402 payments on Base in USDC
- —Users who want low-cost, commitment-free access to financial transaction endpoints
Not for
- —Users who need detailed API documentation or request/response schemas before integrating
- —High-volume consumers who would benefit from subscription-based pricing rather than per-call fees
- —Anyone unable to settle payments in USDC on the Base network
Quick start
curl -X POST https://lowpaymentfee.com/api/v1/portfolios/85/transactions \
-H "Content-Type: application/json" \
-H "X-PAYMENT: <x402-payment-token>"Endpoint
Quality
The endpoint is confirmed live with a valid x402 402 challenge, but there is no OpenAPI schema, no request/response examples, and no meaningful documentation beyond a landing page listing. The actual behavior behind the paywall is entirely unknown.
Warnings
- —No OpenAPI or schema documentation available for this endpoint
- —All doc/API/pricing/README pages return only a 'Connect wallet' prompt with no substantive content
- —The specific functionality of /api/v1/portfolios/85/transactions is undocumented — it is unclear what request body is expected or what response is returned
- —The portfolio ID '85' is hardcoded in the path; it is unknown whether other portfolio IDs are supported
Citations
- —The endpoint returns a valid x402 challenge with maxAmountRequired of 20000 base units of USDC on Basehttps://lowpaymentfee.com/api/v1/portfolios/85/transactions
- —The platform advertises $0.02 per request, no API keys, no rate limits, and instant accesshttps://lowpaymentfee.com
- —USDC asset address 0x833589fCD6eDb6E08f4c7C32D4f71b54bdA02913 on Base networkhttps://lowpaymentfee.com/api/v1/portfolios/85/transactions