x402-gated portfolio transactions endpoint on Base, paid per-call in USDC.
What it does
This endpoint at lowpaymentfee.com provides access to portfolio transaction data via a POST request to `/api/v1/portfolios/92/transactions`. It is part of a broader platform (lowpaymentfee.com) that offers a variety of x402-gated APIs spanning data analytics, AI/ML inference, finance/Web3 data, and infrastructure utilities — all payable per-request in USDC on the Base network with no API keys or rate limits required.
The specific endpoint listed here costs $0.02 per request (20,000 base units of USDC with 6 decimals). Payment is made via the x402 protocol: callers include an `X-PAYMENT` header containing a signed payment proof, and the server verifies it before returning the response. The x402 challenge confirms the endpoint is live, accepts USDC on Base (contract `0x8335…2913`), and uses the "exact" payment scheme with a 300-second timeout.
Documentation on the site 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 schema, no request/response examples, and no description of what the portfolio transactions endpoint actually returns. The endpoint path suggests it retrieves or creates transactions for a specific portfolio (ID 92), but the exact input format and output structure are unknown.
Capabilities
Use cases
- —Retrieving or submitting portfolio transaction records via a pay-per-call model
- —Integrating x402 payment flows into agent-driven financial data pipelines
- —Accessing financial portfolio data without traditional API key management
Fit
Best for
- —Developers experimenting with x402 payment protocol integrations
- —Agents that need on-demand portfolio transaction data with crypto micropayments
- —Use cases where avoiding API key provisioning is desirable
Not for
- —Users needing well-documented, production-grade financial APIs with clear schemas
- —High-volume consumers who need bulk pricing or subscription plans
- —Anyone requiring fiat-only payment rails
Quick start
curl -X POST https://lowpaymentfee.com/api/v1/portfolios/92/transactions \
-H "Content-Type: application/json" \
-H "X-PAYMENT: <x402-payment-proof>" \
-d '{}'Endpoint
Quality
The endpoint is live (402 challenge captured) and pricing is clear ($0.02/request in USDC on Base), but there is no OpenAPI schema, no request/response examples, and all documentation pages return only a wallet-connect prompt. The purpose of the specific portfolio/92/transactions endpoint is unclear beyond what can be inferred from the URL path.
Warnings
- —No OpenAPI schema or endpoint documentation available
- —All doc/pricing/README pages render only 'Connect wallet' with no content
- —The specific function of /api/v1/portfolios/92/transactions is undocumented — input and output formats are unknown
- —Portfolio ID 92 is hardcoded in the path; unclear if other portfolio IDs are accessible
Citations
- —The endpoint returns a 402 challenge with maxAmountRequired of 20000 base units of USDC on Base networkhttps://lowpaymentfee.com/api/v1/portfolios/92/transactions
- —The platform advertises $0.02 per request pricing with no API keys, no rate limits, and instant access on Base networkhttps://lowpaymentfee.com
- —USDC asset contract on Base is 0x833589fCD6eDb6E08f4c7C32D4f71b54bdA02913https://lowpaymentfee.com/api/v1/portfolios/92/transactions