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 the x402 payment protocol. The specific resource `/api/v1/portfolios/2/transactions` accepts POST requests and is gated behind a per-call USDC payment on the Base network. The x402 challenge indicates a maximum cost of 20,000 base units of USDC (0.02 USD per request), consistent with the site-wide pricing of $0.02/request advertised on the provider's landing page.
The provider, lowpaymentfee.com, hosts a broad catalog of x402-gated APIs spanning data analytics, AI/ML inference, finance/Web3, and infrastructure utilities — all at the same $0.02/call price point. This particular endpoint falls under a "portfolios" resource path, suggesting it returns or creates transaction records associated with a specific portfolio (portfolio ID 2). However, the exact request body schema and response format are not documented in the crawled material; the docs, pricing, and API pages all rendered only a "Connect wallet" prompt with no further content.
Payment settles in USDC (contract 0x8335…2913) on Base to address 0x1A2B…85F3. The x402 challenge uses the "exact" scheme with a 300-second timeout. No API keys or rate limits are advertised — access is purely pay-per-request via the x402 payment header. The endpoint is live and returning a valid 402 challenge.
Capabilities
Use cases
- —Retrieving or creating transaction records for a specific portfolio
- —Integrating pay-per-call portfolio data into automated trading or analytics pipelines
- —Agent-driven portfolio management where each data fetch is individually settled on-chain
Fit
Best for
- —Developers wanting keyless, pay-per-request access to portfolio transaction data
- —AI agents that can settle USDC payments on Base autonomously
- —Prototyping or low-volume use cases where $0.02/call is cost-effective
Not for
- —High-volume production workloads where per-call crypto settlement overhead matters
- —Users who need detailed API documentation or guaranteed SLAs before integrating
- —Anyone without a Base-compatible USDC wallet
Quick start
curl -X POST https://lowpaymentfee.com/api/v1/portfolios/2/transactions \
-H "Content-Type: application/json" \
-H "X-PAYMENT: <x402-payment-token>" \
-d '{}'Endpoint
Quality
The endpoint is live and returns a valid x402 402 challenge, but there is no documentation of the request body schema, response format, or what 'portfolios/2/transactions' actually returns. The docs, pricing, and API pages all render only a wallet-connect prompt with no usable content. This is effectively a stub listing.
Warnings
- —No request body schema or response schema documented — the exact purpose and data format of this endpoint are unknown.
- —All documentation pages (docs, api, pricing, README) returned only 'Connect wallet' with no further content.
- —Portfolio ID '2' is hardcoded in the path; unclear if other portfolio IDs are valid or how they are obtained.
- —The provider's catalog lists many diverse endpoints (AI, finance, utilities) all at $0.02 — it is unclear whether these are fully functional or placeholder/demo endpoints.
Citations
- —The x402 challenge returns maxAmountRequired of 20000 base units of USDC on Base (0.02 USD per call)https://lowpaymentfee.com/api/v1/portfolios/2/transactions
- —Site-wide pricing is $0.02 per request with no API keys, no rate limits, and instant accesshttps://lowpaymentfee.com
- —USDC asset contract is 0x833589fCD6eDb6E08f4c7C32D4f71b54bdA02913 on Basehttps://lowpaymentfee.com/api/v1/portfolios/2/transactions