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 access to a "portfolios" resource (ID 30) behind an x402 paywall. The provider operates a broad catalog of pay-per-call APIs spanning data analytics, AI/ML inference, finance/Web3 data, and infrastructure utilities, all priced at $0.02 per request settled in USDC on the Base network. No API keys, accounts, or rate limits are advertised — callers simply attach an x402 payment header to each request.
The specific endpoint `/api/v1/portfolios/30` is listed under the title "Premium API Access" but its exact response payload is undocumented in the crawled material. The x402 challenge confirms the endpoint is live, accepts POST requests, charges a maximum of 20,000 base-unit USDC (i.e. $0.02 given 6 decimals), and returns `application/json`. No OpenAPI schema, detailed field descriptions, or example responses were found in the crawl.
The provider's landing page lists sibling endpoints across categories like sentiment analysis, text summarization, price feeds, gas estimates, geocoding, and more — all at the same $0.02 price point. Documentation pages (`/docs`, `/pricing`, `/api`, `/README`) returned only a "Connect wallet" prompt with no substantive content, so the actual data returned by this portfolio endpoint remains unclear.
Capabilities
Use cases
- —Fetching portfolio data or analytics for portfolio ID 30 via a single paid request
- —Integrating pay-per-call portfolio access into an autonomous agent workflow
- —Testing x402 micropayment flows against a live endpoint on Base
Fit
Best for
- —Agents or developers wanting keyless, pay-per-call API access
- —x402 protocol experimentation on Base with low-cost USDC payments
- —Scenarios where no subscription or account signup is acceptable
Not for
- —Users needing detailed documentation or guaranteed SLA before integrating
- —High-volume batch retrieval where per-request pricing is inefficient
- —Anyone requiring non-crypto payment rails
Quick start
curl -X POST https://lowpaymentfee.com/api/v1/portfolios/30 \
-H "Content-Type: application/json" \
-H "X-PAYMENT: <x402-payment-token>"Endpoint
Quality
The x402 challenge is live and pricing is clear ($0.02 USDC on Base), but there is no OpenAPI schema, no documentation of request/response fields, and the docs pages are empty stubs. The purpose of the 'portfolios/30' resource is not explained anywhere in the crawl, making this effectively a stub listing.
Warnings
- —No documentation available — /docs, /pricing, /api, and /README all return only a 'Connect wallet' prompt with no content.
- —The exact data returned by /api/v1/portfolios/30 is unknown; 'Premium API Access' is the only description provided.
- —No OpenAPI or output schema beyond mime type application/json.
- —Sibling endpoints on the same domain are similarly undocumented.
Citations
- —Endpoint returns 402 with x402 challenge advertising $0.02 USDC on Basehttps://lowpaymentfee.com/api/v1/portfolios/30
- —Provider lists many APIs at $0.02/request with no API keys, no rate limits, on Base networkhttps://lowpaymentfee.com
- —USDC asset contract 0x833589fCD6eDb6E08f4c7C32D4f71b54bdA02913 on Basehttps://lowpaymentfee.com/api/v1/portfolios/30
- —Documentation pages return only 'Connect wallet' with no substantive contenthttps://lowpaymentfee.com/docs