Portfolio transactions API on Base, paid per-call via x402 with USDC.
What it does
This endpoint at lowpaymentfee.com provides access to portfolio transaction data via a POST request to `/api/v1/portfolios/10/transactions`. It is part of a broader platform (lowpaymentfee.com) that offers dozens of pay-per-call APIs spanning data analytics, AI/ML inference, finance/Web3 data, and utility services — all settled on the Base network using USDC through the x402 protocol.
The specific endpoint probed here charges a maximum of $0.02 per request (maxAmountRequired of 20,000 base units of USDC, which has 6 decimals = $0.02). Payment is handled inline via the X-PAYMENT header with no API keys, no rate limits, and no upfront commitments. The x402 challenge confirms the endpoint is live, accepting the "exact" payment scheme on Base mainnet, paying to address 0x1A2B...85F3, with a 300-second timeout.
Documentation is extremely sparse. The crawled docs, API, pricing, and README pages all returned 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's purpose — whether it creates, lists, or manages portfolio transactions — must be inferred from the URL path alone. The platform's landing page confirms the $0.02/request pricing model and lists many sibling endpoints, but provides no technical detail for any of them.
Capabilities
Use cases
- —Retrieving or submitting portfolio transaction records programmatically
- —Integrating portfolio transaction data into automated trading or analytics pipelines
- —Agent-driven portfolio management where per-call payment replaces subscription keys
Fit
Best for
- —Developers wanting keyless, pay-per-use access to portfolio transaction data
- —AI agents that can settle x402 payments on Base with USDC
- —Prototyping financial data integrations without subscription commitments
Not for
- —Users needing detailed API documentation or guaranteed SLAs before integrating
- —High-volume batch processing where per-call pricing may add up quickly
- —Anyone without a Base-compatible USDC wallet or x402 client
Quick start
curl -X POST https://lowpaymentfee.com/api/v1/portfolios/10/transactions \
-H "Content-Type: application/json" \
-H "X-PAYMENT: <x402-payment-token>" \
-d '{}'Endpoint
Quality
The x402 challenge is live and confirms pricing and network details, but there is zero documentation: no OpenAPI schema, no request/response examples, no field descriptions. The endpoint's exact functionality is unknown beyond what the URL path implies. All non-landing crawled pages returned only 'Connect wallet' with no content.
Warnings
- —No API documentation available — docs, pricing, README, and API pages all return only a wallet-connect prompt
- —No OpenAPI or JSON schema describing request or response formats
- —Endpoint purpose (create vs. list transactions, required fields) is entirely unclear
- —The specific endpoint /api/v1/portfolios/10/transactions is not listed on the landing page's API catalog — it may be a demo or test resource
Citations
- —The endpoint returns a 402 x402 challenge with maxAmountRequired of 20000 base units of USDC on Base networkhttps://lowpaymentfee.com/api/v1/portfolios/10/transactions
- —The platform advertises $0.02/request pricing with no API keys, no rate limits, and instant access on Base networkhttps://lowpaymentfee.com
- —USDC contract on Base is 0x833589fCD6eDb6E08f4c7C32D4f71b54bdA02913 with 6 decimalshttps://lowpaymentfee.com/api/v1/portfolios/10/transactions