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 a POST request to `/api/v1/portfolios/72/transactions`. It is part of a broader platform (lowpaymentfee.com) that offers a variety of x402-gated APIs spanning data analytics, AI/ML inference, finance/Web3 data, and infrastructure utilities — all settled on the Base network using USDC.
The specific endpoint probed here returns an x402 challenge with a `maxAmountRequired` of 20,000 base units of USDC (the asset at `0x833589fCD6eDb6E08f4c7C32D4f71b54bdA02913` on Base). Since USDC uses 6 decimals, this translates to $0.02 per request, consistent with the platform's advertised flat pricing of $0.02/request across all endpoints. Payment is made via the x402 `exact` scheme, with no API keys or rate limits required — callers simply attach an `X-PAYMENT` header with a valid payment proof.
Documentation is extremely sparse. The docs, API, pricing, and README pages all render only a "Connect wallet" prompt with no substantive 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 (402 challenge captured), but without documentation 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 project showcasing x402 micropayments across many endpoint categories.
Capabilities
Use cases
- —Fetching transaction history for a specific portfolio via micropayment
- —Integrating pay-per-call portfolio data into trading bots or dashboards
- —Demonstrating x402 payment protocol integration on Base
Fit
Best for
- —Developers experimenting with x402 payment protocol
- —Agents needing on-demand portfolio transaction data without API key management
- —Low-volume, pay-as-you-go access to financial transaction records
Not for
- —Production use cases requiring documented request/response schemas
- —High-volume bulk data export where per-call pricing is inefficient
- —Users who need fiat-only payment options
Quick start
curl -X POST https://lowpaymentfee.com/api/v1/portfolios/72/transactions \
-H "Content-Type: application/json" \
-H "X-PAYMENT: <x402-payment-proof>"Endpoint
Quality
The endpoint is confirmed live with a valid x402 402 challenge, and pricing is clear ($0.02/request in USDC on Base). However, there is no OpenAPI schema, no request/response documentation, no examples, and all doc pages are empty stubs. The specific purpose and data model of the portfolios/72/transactions endpoint is undocumented.
Warnings
- —No OpenAPI or schema documentation available for this endpoint
- —All documentation pages (docs, API, pricing, README) render only 'Connect wallet' with no content
- —The endpoint path includes a hardcoded portfolio ID (72) — unclear if other portfolio IDs are supported
- —Request body format and response payload structure are completely unknown
- —Platform appears to be early-stage or a demo; reliability and data quality are unverified
Citations
- —The endpoint returns an x402 challenge with maxAmountRequired of 20000 base units of USDC on Basehttps://lowpaymentfee.com/api/v1/portfolios/72/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 contract on Base is 0x833589fCD6eDb6E08f4c7C32D4f71b54bdA02913https://lowpaymentfee.com/api/v1/portfolios/72/transactions
- —Documentation pages render only 'Connect wallet' with no substantive contenthttps://lowpaymentfee.com/docs