x402-gated portfolio data endpoint on Base, pay $0.02 per request in USDC.
What it does
This endpoint at lowpaymentfee.com provides access to a specific portfolio resource (portfolio ID 45) via the x402 payment protocol. The endpoint is live and returns a 402 challenge requiring payment in USDC on the Base network. Each request costs $0.02 (20,000 base units of USDC with 6 decimals). Payment is made per-call with no API keys, no rate limits, and no subscriptions required.
The hosting site lowpaymentfee.com offers a broad catalog of x402-gated 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 priced at $0.02 per request and settle in USDC on the Base network. This particular endpoint (/api/v1/portfolios/45) is labeled "Premium API Access" but its exact response payload is undocumented — the crawled docs pages returned only a wallet-connect prompt with no further detail.
Because there is no OpenAPI schema, no example request/response documentation, and no description of what the portfolio resource actually contains, the practical utility of this endpoint is difficult to assess without making a paid call. The x402 challenge confirms the endpoint is live and correctly configured, but the lack of documentation is a significant gap.
Capabilities
Use cases
- —Retrieving portfolio data (ID 45) via a single paid API call
- —Demonstrating x402 payment protocol integration on Base
- —Agent-driven data retrieval with per-call USDC micropayments
Fit
Best for
- —Developers experimenting with x402 payment protocol
- —Agents that can settle USDC payments on Base
- —Use cases needing keyless, pay-per-call API access
Not for
- —Users who need detailed documentation before paying
- —High-volume consumers who need bulk pricing or subscriptions
- —Anyone requiring non-crypto payment methods
Quick start
# The endpoint requires an X-PAYMENT header with a valid x402 payment proof.
# Using curl to see the 402 challenge:
curl -X POST https://lowpaymentfee.com/api/v1/portfolios/45
# Returns 402 with x402 challenge. Supply a signed USDC payment on Base to access.Endpoint
Quality
The x402 challenge is live and pricing is clear ($0.02 USDC on Base), but there is no documentation, no OpenAPI schema, no example request/response, and no description of what portfolio 45 actually returns. The docs, pricing, and README pages all render only a wallet-connect prompt with no content.
Warnings
- —No documentation available — docs, pricing, and README pages all return only a wallet-connect prompt
- —No OpenAPI or output schema describing the response payload
- —The specific content of /api/v1/portfolios/45 is completely undocumented
- —Cannot verify what data is returned without making a paid request
Citations
- —Endpoint returns 402 with x402 challenge requiring USDC on Base network, maxAmountRequired 20000 base unitshttps://lowpaymentfee.com/api/v1/portfolios/45
- —All endpoints priced at $0.02 per request with no API keys, no rate limits, instant access on Base networkhttps://lowpaymentfee.com
- —USDC asset address 0x833589fCD6eDb6E08f4c7C32D4f71b54bdA02913 on Basehttps://lowpaymentfee.com/api/v1/portfolios/45