x402-gated portfolio data endpoint on Base, pay $0.02 per request in USDC.
What it does
This endpoint at lowpaymentfee.com provides access to a "portfolios" resource (specifically portfolio ID 4) via the x402 payment protocol. It is part of a broader platform offering dozens of pay-per-call API endpoints spanning data analytics, AI/ML inference, finance/Web3 data, and infrastructure utilities — all gated behind x402 micropayments on the Base network.
The specific endpoint `/api/v1/portfolios/4` accepts POST requests and returns JSON. Payment is settled in USDC (contract 0x8335…2913 on Base) with a maximum amount of 20,000 base units, which equals $0.02 USD (USDC uses 6 decimals). There are no API keys, no rate limits, and no subscription commitments — each call is independently paid for via the x402 payment header.
The platform advertises a uniform $0.02/request pricing across all its endpoints. Documentation pages exist at /docs, /pricing, and /api but currently render only a "Connect wallet" prompt, so detailed request/response schemas for this specific portfolios endpoint are not publicly documented. The exact data returned by the portfolios endpoint is unclear from available materials — the endpoint title is simply "Premium API Access" with no further specification of the portfolio data structure.
Capabilities
Use cases
- —Fetching portfolio data with per-request USDC micropayments on Base
- —Agent-driven data retrieval without API key management
- —Programmatic access to premium data behind x402 paywall
Fit
Best for
- —Agents or applications that can settle x402 payments in USDC on Base
- —Developers wanting keyless, pay-as-you-go API access
- —Low-volume or sporadic callers who don't want subscriptions
Not for
- —Users who need detailed API documentation before integrating
- —High-volume consumers who need bulk pricing or rate-limit guarantees
- —Anyone without a Base-compatible USDC wallet
Quick start
curl -X POST https://lowpaymentfee.com/api/v1/portfolios/4 \
-H "Content-Type: application/json" \
-H "X-PAYMENT: <x402-payment-token>"Endpoint
Quality
The endpoint is live and returns a valid x402 challenge with clear pricing. However, there is no OpenAPI schema, no documented request/response format, and the docs/pricing/API pages all render only a wallet-connect prompt. The actual data returned by the portfolios endpoint is completely unspecified.
Warnings
- —No request or response schema available — the exact data returned by /api/v1/portfolios/4 is unknown
- —Documentation pages (/docs, /pricing, /api, /README) render only 'Connect wallet' with no usable content
- —The endpoint name 'Premium API Access' is generic and does not describe the actual resource
- —Cannot verify what portfolio data (if any) is actually served behind the paywall
Citations
- —The endpoint returns a 402 challenge with maxAmountRequired of 20000 base units in USDC on Basehttps://lowpaymentfee.com/api/v1/portfolios/4
- —The platform advertises $0.02/request pricing 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/4