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/63` is part of the lowpaymentfee.com platform, which offers a collection of x402-protocol pay-per-request APIs spanning data analytics, AI/ML inference, finance/Web3, and infrastructure utilities. The specific `/portfolios/63` resource is listed under "Premium API Access" but its exact data payload is not documented beyond the generic description. All endpoints on the platform share the same pricing model: $0.02 per request, settled in USDC on the Base network.
The endpoint is live and returns a valid x402 challenge (HTTP 402) requesting payment of 20,000 base units of USDC (0x8335…2913 on Base, 6 decimals = $0.02) via the "exact" scheme. Payment is sent to address 0x1A2B13E97f5F837C8F9FA1F95a1484B7C70d85F3 with a 300-second timeout. The response MIME type is `application/json` and the method is POST. No API key or account registration is needed; access is granted purely through the x402 payment header.
Documentation is extremely sparse — the docs, pricing, API, and README pages all render only a "Connect wallet" prompt with no additional technical detail. There is no OpenAPI spec, no request/response schema, and no description of what the `/portfolios/63` resource actually returns. The platform appears to be a demonstration or early-stage deployment of x402-gated microservices. Without knowing the response schema, callers should treat this as an exploratory endpoint.
Capabilities
Use cases
- —Fetching portfolio data (resource ID 63) via a single paid POST request
- —Demonstrating x402 protocol payment flows on Base
- —Agent-driven data retrieval without pre-registration or API keys
Fit
Best for
- —Developers experimenting with x402 payment protocol
- —Agents that can settle USDC payments on Base L2
- —Use cases requiring keyless, pay-per-request API access
Not for
- —Production workloads requiring documented response schemas
- —Users who need free or subscription-based access
- —Applications needing high-throughput bulk data retrieval (no documented rate limits but per-call payment adds friction)
Quick start
curl -X POST https://lowpaymentfee.com/api/v1/portfolios/63 \
-H "Content-Type: application/json" \
-H "X-PAYMENT: <x402-payment-token>"Endpoint
Quality
The endpoint is live and returns a well-formed x402 challenge, but there is zero documentation on what the /portfolios/63 resource returns, no OpenAPI spec, no request body schema, and no example responses. The docs pages are empty beyond a wallet-connect prompt. This is effectively a stub listing.
Warnings
- —No documentation available — docs, pricing, API, and README pages all show only 'Connect wallet'
- —No OpenAPI or request/response schema provided for this endpoint
- —The exact nature of the 'portfolios/63' resource is unknown — the description is just 'Premium API Access'
- —Platform appears to be early-stage or a demo; reliability and data quality are unverified
Citations
- —The endpoint returns a valid x402 challenge with maxAmountRequired of 20000 base units of USDC on Basehttps://lowpaymentfee.com/api/v1/portfolios/63
- —All endpoints on the platform cost $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/63