x402-gated portfolio endpoint on Base, pay $0.02 per request in USDC — no API keys required.
What it does
This endpoint at lowpaymentfee.com provides access to a specific portfolio resource (`/api/v1/portfolios/52`) via the x402 payment protocol. The endpoint is live and returns a 402 challenge requesting payment in USDC on the Base network. The price per request is $0.02 (20,000 base units of USDC with 6 decimals). Payment is made via the x402 "exact" scheme, settling directly on-chain to the specified wallet address.
lowpaymentfee.com hosts a broader suite of pay-per-call APIs spanning data & analytics, AI & machine learning (sentiment analysis, summarization, classification, embeddings), finance & Web3 (price feeds, exchange rates, token quotes, gas estimates), and infrastructure utilities (geocoding, validation, conversion, generation). All endpoints are listed at $0.02 per request with no API keys, no rate limits, and no minimum commitments.
The specific `/api/v1/portfolios/52` endpoint is not listed on the site's main catalog, and no documentation describes what data it returns. The listing title is simply "Premium API Access" with no further detail. There is no OpenAPI schema, no example request/response, and the docs, pricing, and API pages all render only a "Connect wallet" prompt with no additional content. The actual payload and purpose of this particular portfolio resource remain unclear.
Capabilities
Use cases
- —Fetching portfolio data with per-request USDC micropayments on Base
- —Integrating pay-per-call data access into autonomous agents without API key management
- —Accessing financial or portfolio information via on-chain payment rails
Fit
Best for
- —Agents or developers who want keyless, pay-per-request API access
- —Users already holding USDC on Base who want frictionless micropayments
- —Scenarios requiring censorship-resistant, permissionless API consumption
Not for
- —Users needing detailed documentation or guaranteed SLAs before integrating
- —High-volume consumers who need bulk pricing or subscription discounts
- —Anyone without a Base-compatible wallet and USDC balance
Quick start
curl -X POST https://lowpaymentfee.com/api/v1/portfolios/52 \
-H "Content-Type: application/json" \
-H "X-PAYMENT: <x402-payment-token>"Endpoint
Quality
The endpoint is live (402 challenge confirmed) and pricing is clear ($0.02 USDC on Base). However, there is no OpenAPI schema, no documentation of request/response format, no examples, and the specific portfolio resource is not even listed on the provider's own catalog. The docs pages are empty beyond a wallet-connect prompt. Effectively a stub.
Warnings
- —No documentation exists for /api/v1/portfolios/52 — its purpose and response format are unknown
- —Docs, pricing, API, and README pages all render only 'Connect wallet' with no usable content
- —This specific endpoint is not listed in the provider's own API catalog on the homepage
- —No OpenAPI spec or output schema beyond basic HTTP method metadata
Citations
- —The endpoint returns a 402 challenge requesting 20000 base units of USDC on Base networkhttps://lowpaymentfee.com/api/v1/portfolios/52
- —USDC asset contract on Base is 0x833589fCD6eDb6E08f4c7C32D4f71b54bdA02913https://lowpaymentfee.com/api/v1/portfolios/52
- —All listed endpoints cost $0.02 per request with no API keys, no rate limits, and instant accesshttps://lowpaymentfee.com
- —The site offers APIs across data & analytics, AI & ML, finance & Web3, and infrastructure categorieshttps://lowpaymentfee.com