x402-gated card-transaction endpoint on Base, pay-per-call with USDC.
What it does
This endpoint at lowpaymentfee.com exposes a card transactions resource at `/api/v1/cards/31/transactions` behind the x402 payment protocol. When called without payment, it returns a 402 challenge requesting up to 20,000 base units of USDC (0.02 USD) on the Base network, settled to a specified wallet address. The endpoint accepts HTTP POST requests and returns JSON.
The broader lowpaymentfee.com platform advertises a suite of pay-per-request APIs spanning data & analytics, AI/ML inference (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 listed at $0.02 per request with no API keys, no rate limits, and no commitments — payment is handled entirely via the x402 protocol using USDC on Base.
However, the specific endpoint being listed here (`/api/v1/cards/31/transactions`) does not appear in the site's publicly documented API catalog. Its purpose — whether it relates to virtual card management, transaction history, or something else — is not documented in any crawled page. The docs, pricing, and API pages all returned only a "Connect wallet" prompt with no additional content. Without documentation or schema details for this particular endpoint, its exact functionality remains unclear.
Capabilities
Use cases
- —Retrieving or creating card transaction records via a pay-per-call model
- —Integrating card transaction data into automated agent workflows without API keys
- —Making micropayment-gated API calls settled in USDC on Base
Fit
Best for
- —Agents that can settle x402 payments in USDC on Base
- —Use cases requiring keyless, per-request API access to card transaction data
- —Developers exploring x402 protocol integrations
Not for
- —Users needing well-documented API contracts with full schema definitions
- —High-volume batch processing where per-request micropayments add up
- —Anyone without a Base-compatible USDC wallet
Quick start
curl -X POST https://lowpaymentfee.com/api/v1/cards/31/transactions \
-H "Content-Type: application/json" \
-H "X-PAYMENT: <x402-payment-token>"Endpoint
Quality
The endpoint is live (402 challenge confirmed) and pricing is clear ($0.02 USDC on Base), but this specific path (/api/v1/cards/31/transactions) is not documented anywhere on the site. No request/response schema, no docs, no examples. The crawled docs/pricing/API pages all returned only 'Connect wallet' with no content. Functionality is entirely unclear.
Warnings
- —This specific endpoint (/api/v1/cards/31/transactions) does not appear in the site's public API catalog — its purpose is undocumented.
- —All documentation pages (docs, pricing, API, README) returned only a 'Connect wallet' prompt with no substantive content.
- —No request or response schema is available; callers cannot know what to send or what to expect back.
- —The endpoint path references a specific card ID (31), suggesting it may be a resource-specific route rather than a general-purpose API.
Citations
- —The endpoint returns a 402 challenge requesting up to 20,000 base units of USDC on Base networkhttps://lowpaymentfee.com/api/v1/cards/31/transactions
- —USDC asset contract on Base: 0x833589fCD6eDb6E08f4c7C32D4f71b54bdA02913https://lowpaymentfee.com/api/v1/cards/31/transactions
- —All endpoints listed at $0.02 per request with no API keys, no rate limits, and no commitmentshttps://lowpaymentfee.com
- —The site advertises APIs across data & analytics, AI/ML, finance & Web3, and infrastructure categorieshttps://lowpaymentfee.com