x402-gated portfolio endpoint on Base, pay $0.02 per request in USDC — no API keys required.
What it does
This endpoint at `/api/v1/portfolios/29` is part of the lowpaymentfee.com platform, a collection of x402-protocol pay-per-request APIs spanning data analytics, AI/ML inference, finance/Web3, and infrastructure utilities. The specific `/portfolios/29` resource is listed under "Premium API Access" but its exact data payload is not documented beyond the title. It accepts POST requests and returns JSON.
Payment is handled via the x402 protocol on the Base network using USDC (contract `0x833589fCD6eDb6E08f4c7C32D4f71b54bdA02913`). The maximum amount required per call is 20,000 base units of USDC, which at 6 decimals equals $0.02 USD. There are no API keys, no rate limits, and no subscription commitments — each request is individually settled on-chain. The payment timeout is 300 seconds.
The platform advertises a uniform $0.02/request pricing across all its endpoints. Documentation pages (`/docs`, `/pricing`, `/api`, `/README`) all resolve but contain only a "Connect wallet" prompt with no further technical detail, so the actual request/response schema for this particular endpoint is unknown. Without documentation on what data the portfolios endpoint returns or what POST body it expects, consumers should treat this as exploratory until more information is available.
Capabilities
Use cases
- —Fetching portfolio data (portfolio ID 29) on a pay-per-call basis
- —Agent-driven data retrieval without pre-registration or API keys
- —Programmatic access to premium content gated by on-chain micropayments
Fit
Best for
- —Developers wanting zero-signup, pay-as-you-go API access
- —AI agents that can settle x402 payments autonomously on Base
- —Users who need occasional one-off data requests without subscriptions
Not for
- —High-volume consumers who need bulk/batch pricing
- —Users who need detailed API documentation and request/response schemas before integrating
- —Anyone unable to transact in USDC on the Base network
Quick start
curl -X POST https://lowpaymentfee.com/api/v1/portfolios/29 \
-H "Content-Type: application/json" \
-H "X-PAYMENT: <x402-payment-header>"Endpoint
Quality
The endpoint is live and returns a valid x402 challenge with clear pricing, but there is zero documentation on the request body schema, response format, or what 'portfolios/29' actually returns. Docs pages are all empty 'Connect wallet' stubs.
Warnings
- —No documentation available — /docs, /pricing, /api, and /README all show only 'Connect wallet' with no technical content
- —The exact request body schema and response payload for /api/v1/portfolios/29 are completely unknown
- —The endpoint title 'Premium API Access' is generic and does not describe the actual data returned
- —This specific portfolios endpoint is not listed on the homepage's API catalog, raising questions about its purpose
Citations
- —The endpoint returns a 402 x402 challenge with maxAmountRequired of 20000 base units of USDC on Basehttps://lowpaymentfee.com/api/v1/portfolios/29
- —Platform pricing is $0.02 per request with no API keys, no rate limits, and instant access on Base networkhttps://lowpaymentfee.com
- —USDC asset contract on Base is 0x833589fCD6eDb6E08f4c7C32D4f71b54bdA02913https://lowpaymentfee.com/api/v1/portfolios/29
- —Documentation pages resolve but contain only 'Connect wallet' prompthttps://lowpaymentfee.com/docs