x402-gated portfolio endpoint on Base, pay $0.02 per request in USDC — no API keys needed.
What it does
This endpoint at lowpaymentfee.com provides premium API access to a specific portfolio resource (portfolio ID 24) via the x402 payment protocol. It is part of a broader platform that offers dozens of pay-per-call endpoints spanning data analytics, AI/ML inference, finance/Web3 data, and infrastructure utilities — all gated behind x402 micropayments on the Base network.
The endpoint 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 per request (USDC uses 6 decimals). There are no API keys, no rate limits, and no subscription commitments — callers simply attach an X-PAYMENT header with a valid x402 payment proof. The payment timeout is 300 seconds.
Documentation on the site is extremely thin: 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 beyond the x402 challenge's outputSchema stub, and no example payloads. The exact data returned by the /portfolios/24 resource is unknown — the listing title "Premium API Access" is generic and does not clarify the domain. Callers should expect a JSON response but will need to experiment to discover the actual schema.
Capabilities
Use cases
- —Fetching portfolio data on-demand with per-request USDC micropayments
- —Integrating pay-as-you-go data access into autonomous agents without managing API keys
- —Demonstrating x402 payment protocol integration on Base
Fit
Best for
- —Developers experimenting with x402 micropayment protocol
- —Agents that need keyless, pay-per-call API access
- —Low-volume consumers who want no subscription commitment
Not for
- —Users who need detailed API documentation or guaranteed SLAs before integrating
- —High-volume consumers who would benefit from bulk pricing or subscription plans
- —Anyone without a Base-compatible USDC wallet
Quick start
curl -X POST https://lowpaymentfee.com/api/v1/portfolios/24 \
-H "Content-Type: application/json" \
-H "X-PAYMENT: <x402-payment-proof>"Endpoint
Quality
The endpoint is live (402 challenge captured) and pricing is clear ($0.02 USDC on Base), but there is no OpenAPI spec, no documentation beyond a wallet-connect prompt, no request/response examples, and the purpose of the /portfolios/24 resource is entirely unspecified. This is effectively a stub listing.
Warnings
- —No OpenAPI or schema documentation available — request and response formats are unknown
- —All documentation pages (docs, pricing, API, README) render only 'Connect wallet' with no technical content
- —The specific data returned by /portfolios/24 is undocumented; 'Premium API Access' is a generic label
- —No examples of successful responses are available
Citations
- —The endpoint returns a 402 challenge with maxAmountRequired of 20000 base units in USDC on Base networkhttps://lowpaymentfee.com/api/v1/portfolios/24
- —USDC asset contract is 0x833589fCD6eDb6E08f4c7C32D4f71b54bdA02913 on Basehttps://lowpaymentfee.com/api/v1/portfolios/24
- —Platform advertises $0.02 per request, no API keys, no rate limits, instant access on Base networkhttps://lowpaymentfee.com
- —Documentation, pricing, API, and README pages all show only 'Connect wallet'https://lowpaymentfee.com/docs