Pay-per-call portfolio transactions endpoint on Base via x402, settled in USDC.
What it does
This x402-enabled endpoint at lowpaymentfee.com provides access to portfolio transaction data via a POST request to `/api/v1/portfolios/16/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 by the x402 payment protocol on the Base network.
The specific endpoint probed here charges a maximum of $0.02 per request (20,000 base units of USDC, which has 6 decimals). Payment is settled on-chain to address `0x1A2B13E97f5F837C8F9FA1F95a1484B7C70d85F3` using USDC (contract `0x833589fCD6eDb6E08f4c7C32D4f71b54bdA02913`) on Base. No API keys are required; access is granted instantly upon payment. The platform advertises no rate limits and no minimum commitments.
Documentation is extremely sparse. The crawled docs, API, pricing, and README pages all returned only a "Connect wallet" prompt with no substantive content. There is no OpenAPI schema, no request/response examples, and no description of what fields the transactions endpoint accepts or returns. The endpoint is confirmed live (returns a proper 402 x402 challenge), but without documentation it is unclear what request body is expected or what the response payload looks like. The broader site lists many other endpoints at $0.02 each across categories like sentiment analysis, text summarization, geocoding, and crypto gas estimates, but none have documented schemas either.
Capabilities
Use cases
- —Fetching portfolio transaction history without API key registration
- —Programmatic access to transaction data with per-call USDC micropayments
- —Agent-driven portfolio analysis workflows that pay per request on Base
Fit
Best for
- —Developers wanting zero-signup, pay-as-you-go portfolio data access
- —AI agents that can settle x402 payments autonomously on Base
- —Users who prefer on-chain micropayments over subscription billing
Not for
- —Users needing well-documented API schemas and request/response examples before integration
- —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/16/transactions \
-H "Content-Type: application/json" \
-H "X-PAYMENT: <x402-payment-header>" \
-d '{}'Endpoint
Quality
The endpoint is confirmed live with a valid x402 402 challenge, but there is zero documentation: no OpenAPI schema, no request/response examples, no field descriptions. The docs pages all render only a wallet-connect prompt. The listing is effectively a stub with only pricing and network details available.
Warnings
- —No API documentation available — docs, pricing, README, and API pages all return only a wallet-connect prompt with no content.
- —No request or response schema is published; callers cannot know what fields to send or expect.
- —The endpoint path references a specific portfolio ID (16); it is unclear whether other portfolio IDs are supported or what this data represents.
- —The broader platform lists many endpoints but none appear to have published documentation.
Citations
- —The endpoint returns a 402 x402 challenge with maxAmountRequired of 20000 base units of USDC on Basehttps://lowpaymentfee.com/api/v1/portfolios/16/transactions
- —USDC asset contract is 0x833589fCD6eDb6E08f4c7C32D4f71b54bdA02913 on Basehttps://lowpaymentfee.com/api/v1/portfolios/16/transactions
- —Platform advertises $0.02 per request, no API keys, no rate limits, instant access on Base networkhttps://lowpaymentfee.com
- —Docs, API, pricing, and README pages return only a Connect wallet prompt with no substantive documentationhttps://lowpaymentfee.com/docs