Pay-per-call portfolio transactions endpoint on Base via x402 (USDC, $0.02/request).
What it does
This x402-enabled endpoint at lowpaymentfee.com provides access to portfolio transaction data via a POST request to `/api/v1/portfolios/19/transactions`. It is part of a broader platform offering data & analytics, AI/ML inference, finance/Web3, and infrastructure utility APIs, all priced at $0.02 per request with no API keys, no rate limits, and no commitments required.
Payment is settled on the Base network using USDC (contract `0x833589fCD6eDb6E08f4c7C32D4f71b54bdA02913`). The x402 challenge specifies a `maxAmountRequired` of 20000 base units, which at 6 decimals equals $0.02 USD per call. The endpoint uses the "exact" payment scheme with a 300-second timeout. No OpenAPI schema or detailed documentation was found beyond the landing page listing.
The specific endpoint listed here (`/portfolios/19/transactions`) appears to be a single portfolio's transaction resource. Without further documentation it is unclear what request body fields are accepted or what the response payload looks like. The broader platform advertises categories including analytics metrics, AI sentiment analysis, text summarization, financial price feeds, exchange rates, crypto gas estimates, geocoding, and more — all at the same $0.02 price point. However, the docs, pricing, and API pages returned only a "Connect wallet" prompt with no substantive content.
Capabilities
Use cases
- —Fetching transaction history for a specific portfolio
- —Integrating portfolio transaction data into dashboards or analytics pipelines
- —Agent-driven portfolio monitoring with per-call payment
Fit
Best for
- —Developers wanting keyless, pay-per-use portfolio transaction data
- —AI agents that can settle x402 payments on Base
- —Prototyping financial data integrations without subscription commitments
Not for
- —Production use requiring detailed API documentation and guaranteed SLAs
- —Bulk historical transaction exports (no batch endpoint documented)
- —Users who cannot transact in USDC on the Base network
Quick start
curl -X POST https://lowpaymentfee.com/api/v1/portfolios/19/transactions \
-H "Content-Type: application/json" \
-H "X-PAYMENT: <x402-payment-header>"Endpoint
Quality
The endpoint is live (402 challenge captured) and pricing is clear ($0.02 USDC on Base), but there is no OpenAPI schema, no request/response examples, and the docs pages are empty stubs showing only 'Connect wallet'. The specific purpose of this portfolio transactions endpoint is not documented.
Warnings
- —No OpenAPI or schema documentation available for this endpoint
- —Docs, pricing, and API pages return only a 'Connect wallet' prompt with no content
- —Request body format and response structure are unknown
- —The endpoint path references a hardcoded portfolio ID (19); unclear if this is parameterized or fixed
- —The broader platform lists many endpoints but none have documented schemas
Citations
- —The endpoint returns a 402 challenge with maxAmountRequired of 20000 base units in USDC on Base networkhttps://lowpaymentfee.com/api/v1/portfolios/19/transactions
- —All APIs on the platform are priced at $0.02 per request with no API keys, no rate limits, and instant accesshttps://lowpaymentfee.com
- —USDC asset contract is 0x833589fCD6eDb6E08f4c7C32D4f71b54bdA02913 on Basehttps://lowpaymentfee.com/api/v1/portfolios/19/transactions