x402-gated portfolio transactions endpoint on Base, paid per-call in USDC.
What it does
This endpoint at lowpaymentfee.com exposes a POST-based API for portfolio transactions at `/api/v1/portfolios/57/transactions`. It is part of a broader platform (lowpaymentfee.com) that offers dozens of x402-gated API endpoints spanning data analytics, AI/ML inference, finance/Web3 data, and infrastructure utilities — all payable per-request in USDC on the Base network with no API keys or rate limits.
The specific endpoint probed here returns an x402 challenge requesting up to 20,000 base units of USDC (0x8335…2913 on Base). Since USDC uses 6 decimals, this translates to $0.02 per request, consistent with the site's advertised flat pricing of $0.02/request across all endpoints. Payment is settled on-chain via the x402 "exact" scheme to address 0x1A2B…85F3, with a 300-second timeout window.
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 spec, no request/response schema, and no description of what the "portfolios/57/transactions" resource actually returns or what POST body it expects. The endpoint is live (402 challenge confirmed), but without documentation it is unclear what data or functionality it provides beyond the generic "Premium API Access" label.
Capabilities
Use cases
- —Submitting or retrieving portfolio transaction records via a pay-per-call model
- —Integrating on-chain micropayments into agent workflows that need financial transaction data
- —Programmatic access to portfolio data without API key management
Fit
Best for
- —Agents or developers who want keyless, pay-per-request API access
- —Use cases requiring on-chain USDC micropayments on Base
- —Scenarios where avoiding subscription commitments is preferred
Not for
- —Users who need well-documented APIs with clear request/response schemas
- —High-volume use cases where $0.02/request adds up significantly
- —Anyone needing offline or free access to portfolio data
Quick start
curl -X POST https://lowpaymentfee.com/api/v1/portfolios/57/transactions \
-H "Content-Type: application/json" \
-H "X-PAYMENT: <x402-payment-header>" \
-d '{}'Endpoint
Quality
The endpoint is live and returns a valid x402 challenge with clear pricing, but there is zero documentation on request/response schemas, no OpenAPI spec, and no explanation of what the endpoint actually does. All non-landing crawled pages returned only 'Connect wallet' with no content.
Warnings
- —No documentation available — /docs, /api, /pricing, /README all return only a wallet connect prompt
- —No OpenAPI or request/response schema provided for this endpoint
- —The purpose of /api/v1/portfolios/57/transactions is unclear — 'Premium API Access' is a generic label
- —The hardcoded portfolio ID '57' in the URL suggests this may be a specific resource rather than a general-purpose API
Citations
- —The endpoint returns an x402 challenge with maxAmountRequired of 20000 base units of USDC on Basehttps://lowpaymentfee.com/api/v1/portfolios/57/transactions
- —The site advertises $0.02/request flat pricing with no API keys, no rate limits, and instant access on Base networkhttps://lowpaymentfee.com
- —USDC asset address is 0x833589fCD6eDb6E08f4c7C32D4f71b54bdA02913 on Basehttps://lowpaymentfee.com/api/v1/portfolios/57/transactions