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/57` is part of the lowpaymentfee.com platform, a collection of x402-protocol pay-per-request APIs spanning data analytics, AI/ML inference, finance/Web3, and infrastructure utilities. The specific `/portfolios/57` resource is listed under "Premium API Access" but its exact data payload is not documented beyond the generic description.
The endpoint is live and returns a valid x402 challenge (HTTP 402) requesting payment of 20,000 base units of USDC (0x8335…2913) on the Base network, which equals $0.02 per request (USDC uses 6 decimals). Payment is made via the `exact` scheme to address `0x1A2B13E97f5F837C8F9FA1F95a1484B7C70d85F3`. The response MIME type is `application/json` and the method is POST. No API keys, rate limits, or subscriptions are required — callers simply attach an `X-PAYMENT` header with a valid x402 payment proof.
The broader platform advertises endpoints for metrics, reports, data export, insights, sentiment analysis, text summarization, classification, embeddings, price feeds, exchange rates, token quotes, gas estimates, geocoding, validation, conversion, and generation — all at the same $0.02/request price point. However, documentation is extremely sparse: the docs, API, pricing, and README pages all render only a "Connect wallet" prompt with no further technical detail. There is no OpenAPI spec, no request/response schema, and no example payloads available for this or any other endpoint on the platform.
Capabilities
Use cases
- —Fetching portfolio data (resource ID 57) with per-request USDC micropayments
- —Agent-driven data retrieval without pre-registration or API key management
- —Programmatic access to premium content gated behind x402 payment challenges
Fit
Best for
- —Developers or agents wanting zero-signup, pay-as-you-go API access
- —x402-compatible wallets and agent frameworks on Base
- —Low-volume or exploratory use cases where $0.02/request is economical
Not for
- —Users who need detailed API documentation or request/response schemas before integrating
- —High-volume consumers who need bulk pricing or rate-limit guarantees
- —Anyone without a Base-network USDC wallet or x402-compatible payment client
Quick start
curl -X POST https://lowpaymentfee.com/api/v1/portfolios/57 \
-H "X-PAYMENT: <x402-payment-proof>" \
-H "Content-Type: application/json"Endpoint
Quality
The endpoint is live and returns a well-formed x402 challenge with clear pricing. However, there is no documentation, no OpenAPI spec, no request/response schema, and no examples for this or any endpoint on the platform. The purpose of '/portfolios/57' is entirely opaque beyond the generic 'Premium API Access' label. The docs/pricing/README pages are all blank (wallet-connect only).
Warnings
- —No API documentation available — docs, pricing, and README pages all show only 'Connect wallet' with no content
- —No request body schema or response schema documented for this endpoint
- —The specific data returned by /api/v1/portfolios/57 is unknown; 'Premium API Access' is the only description
- —The broader platform lists many endpoints (AI, finance, utils) but none have public documentation — it is unclear whether they are fully functional
Citations
- —The endpoint returns a valid x402 challenge with maxAmountRequired of 20000 base units of USDC on Basehttps://lowpaymentfee.com/api/v1/portfolios/57
- —All endpoints on the platform are priced at $0.02 per request with no API keys, no rate limits, and instant accesshttps://lowpaymentfee.com
- —The platform offers endpoints across Data & Analytics, AI & Machine Learning, Finance & Web3, and Infrastructure categorieshttps://lowpaymentfee.com
- —Docs, API, pricing, and README pages render only a 'Connect wallet' prompt with no further contenthttps://lowpaymentfee.com/docs