x402-gated portfolio endpoint on Base, pay $0.02 per request in USDC — no API keys needed.
What it does
This endpoint at `/api/v1/portfolios/71` 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/71` 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) with `maxAmountRequired` of 20000 base units of USDC (0x8335…2913 on Base, 6 decimals), which equals $0.02. Payment is made via the x402 `exact` scheme by including an `X-PAYMENT` header. There are no API keys, rate limits, or subscription commitments — each call is independently paid. The response MIME type is `application/json` and the endpoint accepts POST requests.
Documentation on the site is extremely sparse. The docs, pricing, API, and README pages all render only a "Connect wallet" prompt with no additional technical content. There is no OpenAPI spec, no request/response schema, and no example payloads available. The actual data returned by the `/portfolios/71` resource is unknown — it could be a financial portfolio, a curated dataset, or something else entirely. Without documentation or sample responses, integrators will need to make a paid request to discover the response format.
Capabilities
Use cases
- —Fetching portfolio data without managing API keys or subscriptions
- —Agent-driven data retrieval with per-request USDC micropayments on Base
- —Programmatic access to premium content behind x402 payment gates
Fit
Best for
- —Developers wanting zero-signup, pay-as-you-go API access
- —AI agents with Base USDC wallets needing on-demand data
- —Prototyping integrations without rate limits or subscription overhead
Not for
- —Users who need detailed API documentation or response schemas before integrating
- —High-volume consumers who would benefit from bulk pricing or subscriptions
- —Anyone without a Base-compatible USDC wallet
Quick start
curl -X POST https://lowpaymentfee.com/api/v1/portfolios/71 \
-H "X-PAYMENT: <x402-payment-token>" \
-H "Content-Type: application/json"Endpoint
Quality
The endpoint is live and returns a valid x402 challenge, confirming pricing and payment details. However, there is no OpenAPI spec, no request/response schema, no documentation beyond a title, and no example payloads. The actual purpose of '/portfolios/71' is undocumented, making this effectively a stub listing.
Warnings
- —No documentation available — docs, pricing, API, and README pages all show only 'Connect wallet' with no content.
- —The response schema for /api/v1/portfolios/71 is completely unknown; no examples or field descriptions exist.
- —The meaning of 'portfolios/71' (what data it returns) is not documented anywhere in the crawled material.
- —The site lists many endpoint categories but this specific endpoint does not appear in any of the listed categories on the homepage.
Citations
- —The endpoint returns a valid x402 challenge with maxAmountRequired of 20000 base units of USDC on Basehttps://lowpaymentfee.com/api/v1/portfolios/71
- —USDC asset contract on Base is 0x833589fCD6eDb6E08f4c7C32D4f71b54bdA02913https://lowpaymentfee.com/api/v1/portfolios/71
- —All endpoints priced at $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