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 an x402 payment-gated POST request. The specific resource `/api/v1/portfolios/3/transactions` is part of a broader platform that offers dozens of pay-per-request APIs spanning data analytics, AI/ML inference, finance/Web3 data, and infrastructure utilities — all settled on the Base network using USDC.
The x402 challenge confirms the endpoint is live and accepts exact-scheme payments in USDC (contract 0x8335…2913 on Base) with a maximum cost of $0.02 per request (20,000 base units at 6 decimals). Payment is made via the X-PAYMENT header with no API keys or rate limits required. The payTo address is 0x1A2B13E97f5F837C8F9FA1F95a1484B7C70d85F3 and the maximum timeout is 300 seconds.
Documentation is extremely sparse — the docs, API, pricing, and README pages all render 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's purpose (portfolio transactions for portfolio ID 3) can only be inferred from the URL path. The broader site lists many endpoints at $0.02 each but provides no technical documentation for any of them.
Capabilities
Use cases
- —Fetching transaction history for a specific portfolio via paid API call
- —Integrating pay-per-request portfolio data into automated trading or analytics pipelines
- —Agent-driven retrieval of financial transaction records without API key management
Fit
Best for
- —Developers wanting keyless, pay-per-call access to portfolio transaction data
- —AI agents that can settle x402 payments on Base in USDC
- —Projects needing low-friction API access without subscriptions or rate limits
Not for
- —Users who need detailed API documentation or schema definitions before integrating
- —Applications requiring free or high-volume bulk access to transaction data
- —Non-crypto-native consumers who cannot settle USDC payments on Base
Quick start
curl -X POST https://lowpaymentfee.com/api/v1/portfolios/3/transactions \
-H "Content-Type: application/json" \
-H "X-PAYMENT: <x402-payment-token>"Endpoint
Quality
The endpoint is live (402 challenge confirmed) and pricing is clear ($0.02 USDC on Base), but there is zero documentation: no OpenAPI schema, no request/response examples, no description of what the endpoint accepts or returns. The docs pages are empty. This is effectively a stub listing.
Warnings
- —No API documentation available — docs, pricing, and README pages all render only 'Connect wallet' with no content
- —No OpenAPI or request/response schema provided; input and output formats are unknown
- —The specific purpose of portfolio ID 3 is unclear — it may be a demo or placeholder
- —No information on what fields the POST body should contain or what the response looks like
Citations
- —The endpoint returns a 402 challenge with x402Version 1, accepting USDC on Base with maxAmountRequired of 20000 base unitshttps://lowpaymentfee.com/api/v1/portfolios/3/transactions
- —The platform advertises $0.02 per request, no API keys, no rate limits, instant access on Base networkhttps://lowpaymentfee.com
- —USDC asset contract on Base is 0x833589fCD6eDb6E08f4c7C32D4f71b54bdA02913https://lowpaymentfee.com/api/v1/portfolios/3/transactions