x402-gated API platform on Base offering data, AI, finance, and utility endpoints at $0.02/request.
What it does
lowpaymentfee.com is an x402-protocol API marketplace that gates access to a variety of endpoints behind per-request micropayments settled in USDC on the Base network. The specific endpoint at `/api/v1/cards/28` is listed as "Premium API Access" and costs up to $0.02 per call (maxAmountRequired of 20,000 base units of USDC, which has 6 decimals = $0.02). No API keys or rate limits are required; callers simply attach an X-PAYMENT header with a valid x402 payment proof.
The broader platform advertises four categories of endpoints: Data & Analytics (metrics, reports, data export, insights), AI & Machine Learning (sentiment analysis, text 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 the same $0.02/request price point.
The `/api/v1/cards/28` endpoint itself lacks detailed documentation — the docs, pricing, and API 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 this specific "cards" resource returns. The endpoint is confirmed live via a valid 402 challenge, but the actual functionality behind this particular path is unclear from available materials.
Capabilities
Use cases
- —Paying per-request for API access without managing API keys or subscriptions
- —Integrating x402-compatible agents that autonomously purchase API calls on Base
- —Accessing various data, AI, finance, or utility endpoints via a single payment protocol
Fit
Best for
- —Developers wanting zero-commitment, pay-as-you-go API access
- —AI agents with x402 payment capabilities on Base
- —Projects needing low-cost micropayment-gated endpoints
Not for
- —Users who need detailed API documentation or OpenAPI specs before integrating
- —High-volume consumers who prefer subscription-based pricing for cost savings
- —Anyone without a Base-compatible USDC wallet
Quick start
curl -X POST https://lowpaymentfee.com/api/v1/cards/28 \
-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 schema, no request/response examples, and no documentation explaining what /api/v1/cards/28 actually returns. The docs/pricing/API pages are empty beyond a wallet connect prompt. The listing is essentially a stub with confirmed liveness.
Warnings
- —No documentation available for /api/v1/cards/28 — unclear what 'Premium API Access' returns
- —No OpenAPI schema or request/response examples provided
- —Docs, pricing, and API pages render only 'Connect wallet' with no content
- —The 'cards/28' path does not correspond to any of the advertised endpoint categories on the homepage
Citations
- —The endpoint returns a 402 challenge with maxAmountRequired of 20000 base units of USDC on Basehttps://lowpaymentfee.com/api/v1/cards/28
- —USDC asset address 0x833589fCD6eDb6E08f4c7C32D4f71b54bdA02913 on Base networkhttps://lowpaymentfee.com/api/v1/cards/28
- —All endpoints priced at $0.02/request with no API keys, no rate limits, and instant accesshttps://lowpaymentfee.com
- —Platform offers Data & Analytics, AI & ML, Finance & Web3, and Infrastructure endpoint categorieshttps://lowpaymentfee.com