Pay-per-call portfolio transactions API on Base network via x402 protocol, settled in USDC.
What it does
This endpoint at lowpaymentfee.com provides access to portfolio transaction data (portfolio ID 36) via a POST request, gated by the x402 payment protocol. Each call costs $0.02 in USDC on the Base network. No API keys, rate limits, or subscriptions are required — callers simply attach an X-PAYMENT header with a valid x402 payment proof to access the resource.
The endpoint is part of a broader platform (lowpaymentfee.com) that offers multiple pay-per-call APIs spanning data analytics, AI/ML inference, finance/Web3 data, and infrastructure utilities — all priced at $0.02 per request. The specific endpoint listed here targets portfolio transactions, likely returning transaction history or records for a given portfolio.
Documentation is extremely sparse. The site's docs, API, pricing, and README pages all render only a "Connect wallet" prompt with no further technical detail. There is no OpenAPI spec, no request/response schema documentation, and no example payloads available. The endpoint is confirmed live (returns a proper 402 x402 challenge), but the actual input parameters and response format remain unknown.
Capabilities
Use cases
- —Retrieving transaction records for a specific portfolio
- —Integrating portfolio transaction data into automated trading or analytics pipelines
- —Agent-driven portfolio monitoring with per-call payment
Fit
Best for
- —Agents needing on-demand portfolio transaction data without subscription commitments
- —Developers prototyping x402 payment flows on Base
- —Low-volume consumers who prefer pay-per-use over monthly plans
Not for
- —High-frequency bulk data retrieval (no documented batch endpoints)
- —Users who need detailed API documentation or SDKs before integrating
- —Anyone without USDC on Base network
Quick start
curl -X POST https://lowpaymentfee.com/api/v1/portfolios/36/transactions \
-H "Content-Type: application/json" \
-H "X-PAYMENT: <x402_payment_proof>"Endpoint
Quality
The endpoint is confirmed live via a valid 402 x402 challenge, but there is no documentation, no request/response schema, no examples, and no OpenAPI spec. The actual functionality of the endpoint (what it returns, what parameters it accepts) is entirely unknown beyond the URL path and description string.
Warnings
- —No API documentation available — docs page only shows 'Connect wallet'
- —No request or response schema documented
- —No example payloads available
- —Actual endpoint behavior and output format are unknown
- —The specific portfolio ID (36) is hardcoded in the URL with no explanation
Citations
- —Endpoint returns a valid x402 challenge with maxAmountRequired of 20000 base units (USDC, 6 decimals = $0.02) on Base networkhttps://lowpaymentfee.com/api/v1/portfolios/36/transactions
- —Platform advertises $0.02/request pricing with no API keys, no rate limits, and instant access on Base networkhttps://lowpaymentfee.com
- —USDC asset address 0x833589fCD6eDb6E08f4c7C32D4f71b54bdA02913 on Basehttps://lowpaymentfee.com/api/v1/portfolios/36/transactions