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 an x402 payment-gated POST request. The specific resource `/api/v1/portfolios/39/transactions` is part of a broader platform that offers dozens of pay-per-request APIs spanning data analytics, AI/ML inference, finance/Web3 data, and infrastructure utilities — all settled on the Base network using USDC.
The x402 challenge confirms the endpoint is live and accepts payments via the "exact" scheme on Base mainnet. The maximum amount required per call is 20,000 base units of USDC (0x8335…), which at 6 decimals equals $0.02 per request. The platform advertises uniform $0.02/request pricing across all endpoints, with no API keys, no rate limits, and no minimum commitments required.
Documentation is extremely sparse — the /docs, /pricing, /api, 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 fields the transactions endpoint accepts or returns. The endpoint's purpose (portfolio transaction data) can only be inferred from the URL path. Without documentation on request body format or response structure, integrators will need to experiment or contact the provider directly.
Capabilities
Use cases
- —Retrieving transaction history for a specific portfolio
- —Integrating portfolio transaction data into financial dashboards
- —Agent-driven portfolio analysis with per-call USDC payments
Fit
Best for
- —Developers wanting keyless, pay-per-request access to portfolio data
- —AI agents that can settle x402 payments on Base
- —Projects needing low-friction API access without subscriptions
Not for
- —Users who need detailed API documentation or schemas before integrating
- —High-volume consumers who prefer flat-rate or subscription pricing
- —Anyone without a Base-compatible USDC wallet
Quick start
curl -X POST https://lowpaymentfee.com/api/v1/portfolios/39/transactions \
-H "Content-Type: application/json" \
-H "X-PAYMENT: <x402-payment-token>"Endpoint
Quality
The endpoint is live and returns a valid x402 challenge with clear pricing ($0.02/request in USDC on Base). However, there is no OpenAPI schema, no documentation, no request/response examples, and no explanation of what the transactions endpoint actually accepts or returns. The docs pages are all empty wallet-connect prompts. This is effectively a stub listing.
Warnings
- —No API documentation available — /docs, /pricing, /api, and /README pages all show only 'Connect wallet' with no content
- —No OpenAPI or input/output schema provided; request body format and response structure are unknown
- —The specific purpose and data returned by /api/v1/portfolios/39/transactions is inferred solely from the URL path
- —Portfolio ID 39 is hardcoded in the URL — unclear if other portfolio IDs are accessible or what they represent
Citations
- —The endpoint returns a valid x402 challenge with maxAmountRequired of 20000 base units of USDC on Basehttps://lowpaymentfee.com/api/v1/portfolios/39/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 address 0x833589fCD6eDb6E08f4c7C32D4f71b54bdA02913 on Basehttps://lowpaymentfee.com/api/v1/portfolios/39/transactions