x402-gated portfolio endpoint on Base, pay-per-request with USDC at $0.02/call.
What it does
This endpoint at lowpaymentfee.com provides access to a "portfolios" resource (specifically portfolio ID 5) behind an x402 payment wall. The endpoint accepts POST requests and returns JSON. Payment is settled on the Base network using USDC (contract 0x8335…2913) with a maximum amount of 20,000 base units, which equals $0.02 per request (USDC uses 6 decimals). No API keys or rate limits are required — access is granted purely via the x402 payment protocol.
The broader lowpaymentfee.com platform advertises a suite of pay-per-call APIs spanning data analytics, AI/ML inference (sentiment analysis, summarization, classification, embeddings), finance/Web3 data (price feeds, exchange rates, token quotes, gas estimates), and infrastructure utilities (geocoding, validation, conversion, generation). All endpoints are listed at $0.02 per request. However, the specific endpoint being listed here (/api/v1/portfolios/5) is not explicitly described on the site's landing page among those categories, so its exact response payload and purpose are unclear.
Documentation is extremely sparse — the /docs, /api, /pricing, and /README pages all render only a "Connect wallet" prompt with no further content. There is no OpenAPI spec, no example request/response documentation, and no schema beyond what the x402 challenge provides. The endpoint is confirmed live (returns a proper 402 challenge), but the lack of documentation makes it difficult to know what data the portfolio endpoint actually returns.
Capabilities
Use cases
- —Retrieving portfolio data on-demand with per-request USDC micropayments
- —Integrating pay-as-you-go data access into autonomous agents
- —Accessing financial portfolio information without API key management
Fit
Best for
- —Agents that can settle x402 payments on Base with USDC
- —Developers wanting keyless, pay-per-request portfolio data access
- —Low-volume consumers who prefer micropayments over subscriptions
Not for
- —Users needing detailed API documentation or response schemas before integrating
- —High-volume consumers who would benefit from bulk pricing or subscriptions
- —Anyone unable to transact USDC on the Base network
Quick start
curl -X POST https://lowpaymentfee.com/api/v1/portfolios/5 \
-H "X-PAYMENT: <x402-payment-token>" \
-H "Content-Type: application/json"Endpoint
Quality
The endpoint is confirmed live with a valid x402 402 challenge, but documentation is essentially nonexistent — no OpenAPI spec, no example requests/responses, and the specific /portfolios/5 endpoint isn't even listed on the site's landing page. The response schema and purpose must be guessed.
Warnings
- —No documentation available — /docs, /api, /pricing, and /README pages all show only 'Connect wallet' with no content.
- —The /api/v1/portfolios/5 endpoint is not listed among the advertised APIs on the landing page; its purpose and response format are unknown.
- —No OpenAPI spec or response schema provided.
- —No example request or response data available to verify functionality.
Citations
- —The endpoint returns a 402 challenge with x402Version 1, accepting USDC on Base with maxAmountRequired of 20000 base unitshttps://lowpaymentfee.com/api/v1/portfolios/5
- —USDC asset contract is 0x833589fCD6eDb6E08f4c7C32D4f71b54bdA02913 on Basehttps://lowpaymentfee.com/api/v1/portfolios/5
- —All listed APIs are priced at $0.02 per request with no API keys, no rate limits, and instant access on Base networkhttps://lowpaymentfee.com
- —The platform advertises APIs across Data & Analytics, AI & ML, Finance & Web3, and Infrastructure categorieshttps://lowpaymentfee.com