x402-gated portfolio transactions endpoint on Base, pay-per-call with USDC.
What it does
This endpoint at lowpaymentfee.com exposes a POST-based API for portfolio transactions at `/api/v1/portfolios/38/transactions`. 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 gated via the x402 payment protocol on the Base network, settled in USDC.
The specific endpoint probed here returns a valid x402 challenge (HTTP 402) requesting payment of up to 20,000 base units of USDC (0.02 USD, since USDC uses 6 decimals) per request. The payment is sent to address `0x1A2B13E97f5F837C8F9FA1F95a1484B7C70d85F3` on Base. The platform advertises no API keys, no rate limits, and instant access — callers simply attach an `X-PAYMENT` header with a valid x402 payment proof.
Documentation is extremely sparse. The `/docs`, `/api`, `/pricing`, and `/README` pages all render only a "Connect wallet" prompt with no further content. There is no OpenAPI schema, no request/response examples, and no description of what the portfolio transactions endpoint actually accepts or returns. The endpoint path suggests it manages or retrieves transactions for a specific portfolio (ID 38), but the exact input format and output structure are unknown. The platform's landing page confirms the $0.02/request pricing and lists many other endpoints, but provides no technical documentation for any of them.
Capabilities
Use cases
- —Submitting or retrieving portfolio transaction records via a pay-per-call model
- —Integrating x402-gated financial data into agent workflows without API key management
- —Programmatic access to portfolio transaction data settled in USDC on Base
Fit
Best for
- —Developers wanting keyless, pay-per-request API access
- —Agents that can settle x402 payments in USDC on Base
- —Use cases requiring low-cost micro-transactions for financial data
Not for
- —Users needing detailed API documentation or OpenAPI specs before integrating
- —High-volume batch processing where per-request pricing may add up
- —Anyone without a Base-compatible USDC wallet
Quick start
curl -X POST https://lowpaymentfee.com/api/v1/portfolios/38/transactions \
-H "Content-Type: application/json" \
-H "X-PAYMENT: <x402-payment-proof>" \
-d '{}'Endpoint
Quality
The endpoint is live and returns a valid x402 challenge, but there is zero documentation: no OpenAPI schema, no request/response examples, no description of what the endpoint does beyond its URL path. The docs pages are empty. This is effectively a stub listing.
Warnings
- —No API documentation available — /docs, /api, /pricing, and /README pages all show only 'Connect wallet' with no content
- —No OpenAPI or input/output schema provided; request and response formats are completely unknown
- —The endpoint path references a specific portfolio ID (38); it is unclear whether this is a demo or a fixed resource
- —The broader platform lists many endpoints but none have documented schemas or examples
Citations
- —The endpoint returns a valid x402 challenge with maxAmountRequired of 20000 base units of USDC on Basehttps://lowpaymentfee.com/api/v1/portfolios/38/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/38/transactions
- —Documentation pages (/docs, /api, /pricing, /README) render only a 'Connect wallet' prompthttps://lowpaymentfee.com/docs