Pay-per-call portfolio transactions API on Base via x402, settled in USDC at $0.02/request.
What it does
This endpoint at lowpaymentfee.com provides access to portfolio transaction data via a POST request to `/api/v1/portfolios/1/transactions`. It is part of a broader platform offering data & analytics, AI/ML inference, finance/Web3, and infrastructure utility APIs — all gated behind the x402 payment protocol on the Base network.
The endpoint is live and returns a standard x402 challenge (HTTP 402) requiring an `X-PAYMENT` header with a USDC payment on Base. The maximum amount required per call is 20,000 base units of USDC (6 decimals), which equals $0.02 USD. Payment is made to address `0x1A2B13E97f5F837C8F9FA1F95a1484B7C70d85F3` using the USDC contract `0x833589fCD6eDb6E08f4c7C32D4f71b54bdA02913` on Base. The payment scheme is "exact" with a timeout of 300 seconds.
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 transactions) can only be inferred from the URL path. The platform advertises no API keys, no rate limits, and instant access, with a flat $0.02 per request across all endpoints.
Capabilities
Use cases
- —Retrieving portfolio transaction history via a single paid API call
- —Integrating portfolio data into agent workflows without API key management
- —Programmatic access to transaction records with per-call USDC micropayments
Fit
Best for
- —Agents or apps needing keyless, pay-per-use portfolio transaction data
- —Developers who prefer crypto-native micropayment access over subscription billing
- —Quick integration with x402-compatible clients on Base
Not for
- —Users who need detailed API documentation or schema validation before integrating
- —High-volume consumers who would benefit from bulk pricing or subscriptions
- —Anyone without a Base-compatible USDC wallet
Quick start
curl -X POST https://lowpaymentfee.com/api/v1/portfolios/1/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, but there is no OpenAPI schema, no request/response examples, and no meaningful documentation beyond the landing page listing. The actual functionality of the transactions endpoint is entirely opaque.
Warnings
- —No OpenAPI or schema documentation available — request and response formats are unknown
- —All documentation pages (docs, pricing, API, README) render only 'Connect wallet' with no content
- —The specific endpoint path '/api/v1/portfolios/1/transactions' uses a hardcoded portfolio ID '1'; unclear if other portfolio IDs are supported
- —Cannot verify what data the endpoint actually returns without making a paid request
Citations
- —The endpoint returns a 402 challenge requiring USDC payment of 20000 base units (=$0.02) on Base networkhttps://lowpaymentfee.com/api/v1/portfolios/1/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/1/transactions