x402-gated portfolio transactions endpoint on Base, pay $0.02 per request in USDC.
What it does
This endpoint at lowpaymentfee.com provides access to portfolio transaction data via a POST request to `/api/v1/portfolios/9/transactions`. It is part of a broader platform (lowpaymentfee.com) that offers a variety of x402-gated APIs spanning data analytics, AI/ML inference, finance/Web3 data, and infrastructure utilities — all priced at $0.02 per request.
Payment is handled via the x402 protocol on the Base network using USDC (contract `0x833589fCD6eDb6E08f4c7C32D4f71b54bdA02913`). The max amount required per call is 20,000 base units of USDC, which equals $0.02 (USDC uses 6 decimals). No API keys are needed; callers authenticate purely through the x402 payment header. The platform advertises no rate limits and instant access.
The specific functionality of this particular endpoint — portfolio transactions for portfolio ID 9 — is not well-documented. The landing page lists many API categories but does not include this specific route among its featured endpoints. It may be a portfolio-specific transaction log or a way to create/query transactions within a portfolio context. Without further documentation or example responses, the exact request body schema and response format remain unknown.
Capabilities
Use cases
- —Querying or creating transactions within a specific portfolio
- —Integrating portfolio transaction data into automated trading or analytics pipelines
- —Agent-driven portfolio management where per-call payment replaces subscription billing
Fit
Best for
- —Developers wanting keyless, pay-per-use API access settled in USDC on Base
- —AI agents that need to autonomously purchase API calls without pre-registration
- —Users who want low-cost micro-transactions without subscription commitments
Not for
- —Users who need detailed API documentation and response schemas before integrating
- —High-volume consumers who would benefit from bulk pricing or subscription plans
- —Anyone who cannot transact on the Base L2 network
Quick start
curl -X POST https://lowpaymentfee.com/api/v1/portfolios/9/transactions \
-H "Content-Type: application/json" \
-H "X-PAYMENT: <x402-payment-header>" \
-d '{}'Endpoint
Quality
The endpoint is live (returns a valid 402 x402 challenge) and pricing is clear ($0.02 USDC on Base). However, there is no documentation for this specific endpoint — no request schema, no response examples, no description of what portfolio 9 transactions actually returns. The crawled docs/pricing/README pages all rendered as just 'Connect wallet' with no useful content.
Warnings
- —No documentation available for this specific endpoint (/api/v1/portfolios/9/transactions) — its purpose and schema are unknown
- —The endpoint references a hardcoded portfolio ID (9); unclear if other portfolio IDs are available or how they are created
- —All crawled subpages (docs, api, pricing, README) returned only 'Connect wallet' with no substantive content
- —No OpenAPI spec, no example requests or responses available
Citations
- —The endpoint returns a 402 x402 challenge with maxAmountRequired of 20000 base units of USDC on Base networkhttps://lowpaymentfee.com/api/v1/portfolios/9/transactions
- —USDC asset contract on Base is 0x833589fCD6eDb6E08f4c7C32D4f71b54bdA02913https://lowpaymentfee.com/api/v1/portfolios/9/transactions
- —Platform pricing is $0.02 per request with no API keys, no rate limits, and instant accesshttps://lowpaymentfee.com
- —The platform offers APIs across Data & Analytics, AI & ML, Finance & Web3, and Infrastructure categorieshttps://lowpaymentfee.com