x402-gated portfolio transactions endpoint on Base, pay-per-call with USDC.
What it does
This endpoint at lowpaymentfee.com provides access to portfolio transaction data via the x402 payment protocol. The specific resource `/api/v1/portfolios/78/transactions` accepts POST requests and charges up to $0.02 per call in USDC on the Base network. Payment is handled inline via the x402 challenge-response mechanism — no API keys, accounts, or rate limits are required.
The hosting site lowpaymentfee.com offers a broad catalog of x402-gated APIs spanning data analytics, AI/ML inference, finance/Web3 data, and infrastructure utilities, all priced at $0.02 per request. However, this specific endpoint falls under a "portfolios" path that is not listed on the site's main catalog page, so its exact response schema and data content are unclear. The x402 challenge confirms it is live and accepts POST with JSON output, settling payments to address 0x1A2B13E97f5F837C8F9FA1F95a1484B7C70d85F3 using USDC (contract 0x833589fCD6eDb6E08f4c7C32D4f71b54bdA02913) on Base.
Documentation beyond the landing page is essentially empty (all sub-pages just show "Connect wallet"), so the request body schema, response fields, and exact data returned are unknown. Agents should treat this as a minimally documented endpoint with confirmed liveness.
Capabilities
Use cases
- —Fetching transaction history for a specific portfolio via a single paid call
- —Integrating portfolio data into an agent workflow without managing API keys
- —Programmatic access to financial transaction records with crypto micropayments
Fit
Best for
- —Agents that can settle x402 payments in USDC on Base
- —Use cases needing keyless, pay-per-call access to portfolio data
- —Developers exploring x402 protocol integrations
Not for
- —Users needing detailed API documentation or guaranteed response schemas
- —High-volume batch retrieval where per-call pricing is inefficient
- —Anyone without a Base-compatible USDC wallet
Quick start
curl -X POST https://lowpaymentfee.com/api/v1/portfolios/78/transactions \
-H "Content-Type: application/json" \
-H "X-PAYMENT: <x402-payment-token>"Endpoint
Quality
The x402 challenge is live and confirms pricing and settlement details, but the endpoint path (/portfolios/78/transactions) is not documented on the site, no request/response schema is available, and all documentation pages are empty. This is effectively a stub listing with confirmed liveness.
Warnings
- —Endpoint path /api/v1/portfolios/78/transactions is not listed in the site's public API catalog — may be an internal or deprecated resource
- —All documentation pages (/docs, /api, /pricing, /README) return only 'Connect wallet' with no actual content
- —No request body schema or response schema is documented anywhere
- —The portfolio ID '78' is hardcoded in the path — unclear if other portfolio IDs are valid
Citations
- —The endpoint returns a 402 challenge with maxAmountRequired of 20000 base units (USDC, 6 decimals = $0.02) on Base networkhttps://lowpaymentfee.com/api/v1/portfolios/78/transactions
- —The site advertises $0.02 per request with no API keys, no rate limits, and instant access on Base networkhttps://lowpaymentfee.com
- —USDC asset contract is 0x833589fCD6eDb6E08f4c7C32D4f71b54bdA02913https://lowpaymentfee.com/api/v1/portfolios/78/transactions