x402-gated portfolio endpoint on Base, pay-per-request with USDC.
What it does
This endpoint at `/api/v1/portfolios/28` is part of the lowpaymentfee.com platform, which offers a suite of x402-protocol pay-per-call APIs spanning data analytics, AI/ML inference, finance/Web3 data, and infrastructure utilities. The specific `/portfolios/28` resource is labeled "Premium API Access" and accepts POST requests, returning JSON. Payment is settled on the Base network using USDC (contract `0x8335…2913`) via the x402 exact-payment scheme.
The x402 challenge advertises a `maxAmountRequired` of 20,000 base units. Since USDC uses 6 decimals, this converts to $0.02 per request — consistent with the site-wide pricing of $0.02/request displayed on the landing page. The platform advertises no API keys, no rate limits, and instant access. However, the crawled documentation, pricing, and README pages all returned only a "Connect wallet" prompt with no substantive content, so there is very little detail on what data this particular portfolio endpoint actually returns or what input parameters it expects.
Because the endpoint path suggests portfolio data (possibly financial portfolio information) but no schema, example responses, or detailed documentation were found, the actual payload structure remains unknown. The endpoint is confirmed live via a valid 402 challenge response.
Capabilities
Use cases
- —Fetching portfolio data via a single pay-per-call request without API key registration
- —Integrating paid data endpoints into autonomous agent workflows using x402 protocol
- —Accessing financial or portfolio information settled on Base L2 with USDC
Fit
Best for
- —Agents or developers wanting keyless, pay-per-request API access
- —x402-compatible clients on the Base network
- —Low-friction micropayment API consumption at $0.02/call
Not for
- —Users needing detailed API documentation or schema guarantees before integration
- —High-volume consumers who need bulk pricing or subscription plans
- —Non-crypto users without access to USDC on Base
Quick start
# The endpoint requires an X-PAYMENT header with a valid x402 payment proof.
# Using curl as an example (you need an x402-compatible client to generate the header):
curl -X POST https://lowpaymentfee.com/api/v1/portfolios/28 \
-H "Content-Type: application/json" \
-H "X-PAYMENT: <x402_payment_token>"Endpoint
Quality
The endpoint is confirmed live with a valid x402 402 challenge, and pricing is clear ($0.02/request in USDC on Base). However, there is no documentation, no input/output schema, no example responses, and the docs/pricing/README pages all returned only 'Connect wallet' with no content. The purpose of the /portfolios/28 resource is unclear beyond the generic 'Premium API Access' label.
Warnings
- —No documentation available — docs, pricing, and README pages all render only a 'Connect wallet' prompt with no substantive content.
- —No input or output schema provided; the actual data returned by /api/v1/portfolios/28 is unknown.
- —The endpoint name 'Premium API Access' is generic and does not describe what data is served.
- —This specific endpoint (/portfolios/28) is not listed on the site's landing page among the advertised APIs, raising questions about its intended use.
Citations
- —The x402 challenge returns maxAmountRequired of 20000 base units in USDC on Base networkhttps://lowpaymentfee.com/api/v1/portfolios/28
- —USDC asset contract is 0x833589fCD6eDb6E08f4c7C32D4f71b54bdA02913 on Basehttps://lowpaymentfee.com/api/v1/portfolios/28
- —Site-wide pricing is $0.02 per request with no API keys, no rate limits, and instant accesshttps://lowpaymentfee.com
- —Platform offers APIs across Data & Analytics, AI & ML, Finance & Web3, and Infrastructure categorieshttps://lowpaymentfee.com