Portfolio transactions endpoint on Base, paid per-call via x402 with USDC.
What it does
This endpoint at lowpaymentfee.com exposes a POST-based transactions resource for portfolio #66. It is part of a broader platform (lowpaymentfee.com) that offers dozens of pay-per-request APIs spanning data analytics, AI/ML inference, finance/Web3 data, and utility services — all settled via the x402 protocol on the Base network using USDC.
The specific endpoint `/api/v1/portfolios/66/transactions` accepts POST requests and costs up to $0.02 per call (maxAmountRequired of 20,000 base units of USDC, which has 6 decimals = $0.02). Payment is made inline via the X-PAYMENT header using the x402 "exact" scheme, settling to address `0x1A2B13E97f5F837C8F9FA1F95a1484B7C70d85F3` on Base. The endpoint was confirmed live, returning a proper 402 challenge.
Documentation is extremely sparse. The crawled docs, API, pricing, and README pages all returned only a "Connect wallet" prompt with no additional content. The portfolio transactions endpoint itself is not listed on the homepage's catalog of available APIs, so its exact input schema and response format are unknown. The platform advertises no API keys, no rate limits, and instant access at a flat $0.02/request price point across all endpoints.
Capabilities
Use cases
- —Submitting or retrieving transactions for a specific portfolio via a pay-per-call model
- —Integrating micropayment-gated financial data into agent workflows
- —Building automated portfolio management pipelines that settle per-request on Base
Fit
Best for
- —Agents needing pay-per-use portfolio transaction access without API key registration
- —Developers experimenting with x402 payment flows on Base
- —Low-volume or bursty workloads where flat per-request pricing is preferable to subscriptions
Not for
- —High-volume bulk transaction processing where per-call fees add up quickly
- —Users who need detailed API documentation or guaranteed SLAs before integrating
- —Anyone without a Base-compatible USDC wallet
Quick start
curl -X POST https://lowpaymentfee.com/api/v1/portfolios/66/transactions \
-H "Content-Type: application/json" \
-H "X-PAYMENT: <x402-payment-token>" \
-d '{}'Endpoint
Quality
The endpoint is live and returns a valid x402 402 challenge, but there is no documentation, no OpenAPI schema, no request/response examples, and the specific portfolio transactions endpoint is not even listed on the provider's homepage. The purpose and input/output format must be entirely guessed.
Warnings
- —No documentation available — docs, API, pricing, and README pages all return only a wallet-connect prompt with no content.
- —The endpoint /api/v1/portfolios/66/transactions is not listed among the provider's advertised APIs on the homepage; its purpose is unclear.
- —No request or response schema is available; input format is unknown.
- —The hardcoded portfolio ID (66) suggests this may be a specific resource rather than a general-purpose API.
Citations
- —The endpoint returns a valid x402 402 challenge with maxAmountRequired of 20000 base units of USDC on Basehttps://lowpaymentfee.com/api/v1/portfolios/66/transactions
- —The platform advertises $0.02/request pricing with no API keys, no rate limits, and instant accesshttps://lowpaymentfee.com
- —USDC asset contract on Base is 0x833589fCD6eDb6E08f4c7C32D4f71b54bdA02913https://lowpaymentfee.com/api/v1/portfolios/66/transactions
- —Docs, API, pricing, and README pages return only a Connect wallet prompthttps://lowpaymentfee.com/docs