x402-gated portfolio endpoint on Base, pay-per-request with USDC.
What it does
This endpoint at lowpaymentfee.com provides a "Premium API Access" resource at `/api/v1/portfolios/75` via the x402 payment protocol. It is live and returns a proper 402 challenge when called without payment. The endpoint accepts POST requests and settles payments in USDC on the Base network. The price per request is $0.02 (20,000 base units of USDC with 6 decimals), consistent with the provider's uniform pricing across all their API endpoints.
The provider, lowpaymentfee.com, hosts a broad catalog of pay-per-call APIs spanning data & analytics, AI/ML (sentiment analysis, summarization, classification, embeddings), finance & Web3 (price feeds, exchange rates, token quotes, gas estimates), and infrastructure utilities (geocoding, validation, conversion, generation). All endpoints share the same $0.02/request pricing with no API keys, no rate limits, and no minimum commitments. Payments are made via the x402 exact-payment scheme on Base.
The specific `/api/v1/portfolios/75` endpoint is listed under "Premium API Access" but its exact data payload is not documented in the crawled material. There is no OpenAPI schema, no request/response examples, and the docs, pricing, and API pages all render only a "Connect wallet" prompt with no further content. The endpoint's purpose — likely returning portfolio-related data given the URL path — must be inferred from the URL structure alone. The output MIME type is `application/json`.
Capabilities
Use cases
- —Fetching portfolio data on-demand with per-request USDC micropayments
- —Agent-driven data retrieval without API key management
- —Programmatic access to portfolio information via x402 protocol
Fit
Best for
- —Developers or agents wanting keyless, pay-per-use API access
- —x402-compatible clients on the Base network
- —Low-friction data retrieval without subscription commitments
Not for
- —Users needing detailed API documentation or schema validation before integration
- —High-volume consumers who would benefit from bulk pricing or subscriptions
- —Anyone without a Base-network USDC wallet
Quick start
curl -X POST https://lowpaymentfee.com/api/v1/portfolios/75 \
-H "Content-Type: application/json" \
-H "X-PAYMENT: <x402-payment-header>"Endpoint
Quality
The endpoint is live and returns a valid x402 402 challenge with clear pricing. However, there is no OpenAPI schema, no request/response examples, and the docs pages are empty (only 'Connect wallet'). The specific purpose of /api/v1/portfolios/75 is undocumented, making this effectively a stub listing.
Warnings
- —No documentation available — docs, pricing, API, and README pages all render only 'Connect wallet'
- —No OpenAPI or request/response schema provided for this endpoint
- —The exact data returned by /api/v1/portfolios/75 is unknown; 'Premium API Access' is the only description
- —Portfolio ID 75 is hardcoded in the URL with no explanation of what it represents
Citations
- —The endpoint returns a 402 challenge with x402Version 1, exact scheme, on Base network, with maxAmountRequired of 20000 in USDChttps://lowpaymentfee.com/api/v1/portfolios/75
- —All endpoints on lowpaymentfee.com are priced at $0.02/request with no API keys, no rate limits, and instant access on the Base networkhttps://lowpaymentfee.com
- —The USDC asset contract on Base is 0x833589fCD6eDb6E08f4c7C32D4f71b54bdA02913https://lowpaymentfee.com/api/v1/portfolios/75