x402-gated portfolio endpoint on Base, pay $0.02 per request in USDC — no API keys required.
What it does
This endpoint at `/api/v1/portfolios/17` is part of the lowpaymentfee.com platform, a collection of x402-protocol pay-per-call APIs spanning data analytics, AI/ML inference, finance/Web3, and infrastructure utilities. The specific portfolio endpoint (ID 17) is listed under "Premium API Access" and accepts POST requests, returning JSON responses.
Payment is settled on the Base network using USDC (contract `0x833589fCD6eDb6E08f4c7C32D4f71b54bdA02913`) via the x402 exact-payment scheme. The maximum amount required per call is 20,000 base units of USDC (6 decimals), which equals $0.02 USD. The platform advertises no API keys, no rate limits, and instant access — callers simply attach an `X-PAYMENT` header with a valid x402 payment proof.
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 request/response schema documentation, and no explanation of what the portfolios resource actually returns. The endpoint is confirmed live (returns 402 challenge), but the actual data behind it — what a "portfolio" is, what fields are returned, what POST body is expected — is entirely unknown from available materials.
Capabilities
Use cases
- —Fetching portfolio data via a single micropayment without needing an API key or subscription
- —Integrating pay-per-call data access into autonomous agents that hold USDC on Base
- —Demonstrating x402 protocol payment flows for developer tooling
Fit
Best for
- —Developers experimenting with x402 pay-per-request protocols
- —Agents with USDC on Base that need on-demand data access without credentials
- —Low-volume callers who want to avoid API key management and subscriptions
Not for
- —Users who need detailed documentation or schema guarantees before integrating
- —High-volume consumers who would benefit from bulk pricing or subscription plans
- —Anyone without a Base-network USDC wallet
Quick start
curl -X POST https://lowpaymentfee.com/api/v1/portfolios/17 \
-H "Content-Type: application/json" \
-H "X-PAYMENT: <x402-payment-proof>"Endpoint
Quality
The endpoint is confirmed live via a valid 402 challenge, and pricing is clear ($0.02 USDC on Base). However, there is no OpenAPI spec, no request/response schema, no documentation beyond a wallet-connect prompt, and no indication of what data the portfolios/17 resource actually returns. This is effectively a stub listing.
Warnings
- —No documentation available — /docs, /pricing, /api, and /README all render only 'Connect wallet' with no content
- —No OpenAPI or schema definition; request body and response structure are completely unknown
- —The specific resource 'portfolios/17' is not listed on the homepage — its purpose and data content are unclear
- —No examples or sample responses available anywhere in crawled materials
Citations
- —The endpoint returns a 402 challenge with x402Version 1, requiring USDC payment on Base networkhttps://lowpaymentfee.com/api/v1/portfolios/17
- —maxAmountRequired is 20000 base units of USDC (6 decimals) = $0.02https://lowpaymentfee.com/api/v1/portfolios/17
- —Platform advertises $0.02/request pricing with no API keys, no rate limits, and instant accesshttps://lowpaymentfee.com
- —USDC asset contract is 0x833589fCD6eDb6E08f4c7C32D4f71b54bdA02913 on Basehttps://lowpaymentfee.com/api/v1/portfolios/17
- —Docs, pricing, API, and README pages show only 'Connect wallet' with no further contenthttps://lowpaymentfee.com/docs