x402-gated portfolio transactions endpoint on Base, pay-per-call with USDC.
What it does
This endpoint at lowpaymentfee.com exposes a POST-based transactions API for portfolio #52 via the x402 payment protocol. 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 infrastructure utilities — all gated behind x402 challenges settled in USDC on the Base network.
The specific endpoint `/api/v1/portfolios/52/transactions` returns an x402 challenge requesting up to 20,000 base units of USDC (0x8335…2913 on Base). Since USDC uses 6 decimals, this translates to $0.02 per request, consistent with the site's advertised flat pricing of $0.02/request across all endpoints. Payment is made via the x402 "exact" scheme, with a 300-second timeout window. No API keys or rate limits are required; access is granted immediately upon valid payment.
Documentation on the site is extremely thin — the docs, API, pricing, and README pages all render only a "Connect wallet" prompt with no further technical detail. There is no OpenAPI spec, no request/response schema, and no usage examples available from the crawl. The endpoint's purpose ("Premium API Access" for portfolio transactions) is vague, and it is unclear what request body is expected or what the response payload looks like. The platform appears to be a demonstration or early-stage x402 API marketplace.
Capabilities
Use cases
- —Submitting or retrieving transactions for a specific portfolio via paid API call
- —Demonstrating x402 payment protocol integration for agent-to-agent commerce
- —Testing micropayment-gated API workflows on Base L2
Fit
Best for
- —Developers experimenting with x402 payment protocol
- —Agents needing pay-per-call portfolio transaction access without API keys
- —Projects exploring USDC micropayments on Base
Not for
- —Production portfolio management requiring documented schemas and SLAs
- —Users who need detailed API documentation or OpenAPI specs before integrating
- —High-volume use cases where per-request pricing may not be cost-effective
Quick start
curl -X POST https://lowpaymentfee.com/api/v1/portfolios/52/transactions \
-H "Content-Type: application/json" \
-H "X-PAYMENT: <x402-payment-header>" \
-d '{}'Endpoint
Quality
The endpoint is live and returns a valid x402 challenge, but there is no OpenAPI spec, no request/response schema, no documentation beyond a wallet-connect prompt, and the endpoint's actual functionality (what data it accepts or returns) is entirely undocumented. This is effectively a stub listing.
Warnings
- —No OpenAPI or schema documentation available — request and response formats are unknown
- —All documentation pages (docs, API, pricing, README) render only 'Connect wallet' with no content
- —The specific purpose of 'portfolios/52/transactions' is unclear — may be a demo or placeholder
- —No examples of successful responses are available
Citations
- —The endpoint returns an x402 challenge with maxAmountRequired of 20000 base units of USDC on Basehttps://lowpaymentfee.com/api/v1/portfolios/52/transactions
- —The platform advertises $0.02/request flat pricing with no API keys, no rate limits, and instant access on Base networkhttps://lowpaymentfee.com
- —USDC asset address is 0x833589fCD6eDb6E08f4c7C32D4f71b54bdA02913 on Basehttps://lowpaymentfee.com/api/v1/portfolios/52/transactions