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/12/transactions` is part of a broader platform that offers dozens of pay-per-request APIs spanning data analytics, AI/ML inference, finance, crypto, and utility services — all settled on the Base network using USDC.
The x402 challenge confirms the endpoint is live and accepts exact-scheme payments on Base. The maximum amount required per call is 20,000 base units of USDC (0x8335…), which equals $0.02 given USDC's 6 decimals. This matches the site's advertised flat rate of $0.02 per request across all endpoints. The platform advertises no API keys, no rate limits, and instant access.
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 spec, no request/response schema, and no usage examples. The endpoint path suggests it returns transaction records for portfolio ID 12, but the exact request body format and response structure are unknown. The platform appears to be a demonstration or early-stage service; the specific portfolio endpoint may return mock or sample data.
Capabilities
Use cases
- —Fetching transaction history for a specific portfolio via a single paid API call
- —Integrating pay-per-request financial data into agent workflows without API key management
- —Demonstrating x402 protocol payment flows on Base with USDC
Fit
Best for
- —Developers exploring x402 payment protocol integrations
- —Agents needing keyless, pay-per-call access to portfolio data
- —Prototyping micropayment-gated API architectures
Not for
- —Production portfolio management requiring documented, stable schemas
- —Users needing free or subscription-based access to financial data
- —High-volume batch retrieval of transaction records (no documented bulk endpoint)
Quick start
curl -X POST https://lowpaymentfee.com/api/v1/portfolios/12/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 USDC on Base). However, there is no OpenAPI spec, no request/response schema, no documentation beyond a wallet-connect prompt, and no examples. The purpose of the specific portfolio/transactions resource is only inferable from the URL path.
Warnings
- —No OpenAPI spec or request/response schema available
- —All documentation pages (docs, API, pricing, README) render only 'Connect wallet' with no content
- —The specific portfolio ID 12 may be a demo/sample resource — unclear if it returns real data
- —Platform appears early-stage; stability and longevity are uncertain
Citations
- —The endpoint returns a 402 x402 challenge with maxAmountRequired of 20000 base units of USDC on Basehttps://lowpaymentfee.com/api/v1/portfolios/12/transactions
- —The platform advertises $0.02 per request, no API keys, no rate limits, instant access, Base networkhttps://lowpaymentfee.com
- —USDC asset address 0x833589fCD6eDb6E08f4c7C32D4f71b54bdA02913 on Basehttps://lowpaymentfee.com/api/v1/portfolios/12/transactions